Cunningham v The Commonwealth - [2016] HCA 39

HIGH COURT OF AUSTRALIA
FRENCH CJ,
KIEFEL, BELL, GAGELER, KEANE, NETTLE AND GORDON JJ
BARRY THOMAS CUNNINGHAM & ORS PLAINTIFFS
AND
COMMONWEALTH OF AUSTRALIA & ANOR DEFENDANTS
Cunningham v Commonwealth of Australia
[2016] HCA 39
12 October 2016
S140/2015
ORDER
The questions stated by the parties in the special case dated 4 February 2016 and referred for consideration by the Full Court be answered as follows:
Question One

Do any, and if so which, of the following laws and Determinations of the Remuneration Tribunal constitute or authorise an acquisition of any, and if so what, property of the plaintiffs, or any of them, otherwise than on just terms, within the meaning of s 51(xxxi) of the Constitution:
a.Remuneration Tribunal Act 1973 (Cth), ss 7(1A), 7(1B), 7(1C) and 7(2A);
b.Remuneration and Other Legislation Amendment Act 2011 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 16A, 17A, 19, 20, 21(2));
c.Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 2, 3, 5, 6, 7, 8 and 9);

d.Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 11(2) (as originally enacted);
e.Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 1, item 6);
f.Determination 2012/02, Pt 2 (cl 2.2);
g.Determination 2012/03, Pt 2 (cl 2.3), Pt 3 (cl 3.1);
h.Determination 2012/15, Pt 1 (cl 1.3 and cl 1.4 (insofar as it relates to cl 1.3));
i.Determination 2013/13, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
j.Determination 2014/10, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
k.Determination 2015/06, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1)?

Answer
No.
Question Two

If the answer to Question One is yes, to what, if any relief are the plaintiffs, or any of them, entitled in the proceedings?
Answer
Unnecessary to answer.
Question Three
Who should pay the costs of the proceedings?
Answer
The plaintiffs.

Representation
A J Myers QC and T O Prince for the plaintiffs (instructed by Hazan Hollander)
J T Gleeson SC, Solicitor-General of the Commonwealth and D F C Thomas for the first defendant (instructed by Australian Government Solicitor)
Submitting appearance for the second defendant
Notice: This copy of the Court's Reasons for Judgment is subject to formal revision prior to publication in the Commonwealth Law Reports.

CATCHWORDS
Cunningham v Commonwealth of Australia
Constitutional law (Cth) – Legislative power – Acquisition of property on just terms – Where amendments to Parliamentary Contributory Superannuation Act 1948 (Cth) and Remuneration Tribunal Act 1973 (Cth) and Determinations by Remuneration Tribunal modified method by which allowances paid to retired members of Parliament calculated – Where enactment of and subsequent amendment to Members of Parliament (Life Gold Pass) Act 2002 (Cth) modified entitlement conferred on retired members of Parliament to payment of travel expenses – Whether amendments and Determinations constitute or authorise acquisition of property otherwise than on just terms within meaning of s 51(xxxi) of Constitution.
Words and phrases – "acquisition of property", "inherently defeasible", "inherently liable to variation", "just terms", "Life Gold Pass", "parliamentary allowance", "property", "retiring allowance", "subject to this Act", "until the Parliament otherwise provides".
Constitution, ss 48, 51(xxxi), 51(xxxvi), 66.
Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 11(2).
Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3.
Parliamentary Contributory Superannuation Act 1948 (Cth), ss 18, 22T.
Remuneration and Other Legislation Amendment Act 2011 (Cth), s 3.
Remuneration Tribunal Act 1973 (Cth), ss 7(1A), 7(1B), 7(1C), 7(2A).

FRENCH CJ, KIEFEL AND BELL JJ. Each of the four plaintiffs served as a member of the House of Representatives of the Commonwealth Parliament for not less than eight years between 1969 and 2001, although in the case of the first and second plaintiffs, their service was over two separate periods. Three of the plaintiffs also held parliamentary offices and two were Ministers of State for a time.
Whilst serving as members of Parliament the plaintiffs became entitled to, and received, a parliamentary allowance and a parliamentary office holder allowance and/or a ministerial salary under various legislation as amended from time to time[1]. In addition the plaintiffs also received certain other entitlements, such as for travel, accommodation and office facilities. Whilst in receipt of the parliamentary allowance and, where relevant, parliamentary office holder allowance and/or ministerial salary, the plaintiffs paid a proportion of what was received to the Commonwealth pursuant to the Parliamentary Contributory Superannuation Act 1948 (Cth) ("the Superannuation Act")[2].
[1]Parliamentary Allowances Act 1952 (Cth); Remuneration Tribunal Act 1973 (Cth); Remuneration and Allowances Act 1990 (Cth); Ministers of State Act 1952 (Cth).
[2]Parliamentary Contributory Superannuation Act 1948 (Cth), ss 13-14.
On ceasing to serve as a member of Parliament, whether because they were not re-elected or had resigned, each of the plaintiffs became entitled to a retiring allowance under the Superannuation Act, together with an additional retiring allowance for former parliamentary office holders and/or Ministers of State (together the "retiring allowances")[3]. The fourth and third plaintiffs, who retired respectively in 1990 and 2001, were also entitled on retirement to use a "Life Gold Pass" for domestic travel at Commonwealth expense.
[3]Parliamentary Contributory Superannuation Act 1948 (Cth), s 18.
The plaintiffs contend that they have rights in the nature of property, within the meaning of s 51(xxxi) of the Constitution, in respect of their retiring allowances and, in the case of the third and fourth plaintiffs, their Life Gold Passes. The plaintiffs further contend that changes made by certain legislative provisions[4] and by Determinations made by the Remuneration Tribunal pursuant to the Remuneration Tribunal Act 1973 (Cth)[5] ("the Remuneration Tribunal Act") effect alterations of those property rights or interests which amount to acquisitions of their property otherwise than on just terms, within the meaning of s 51(xxxi)[6].
[4]Remuneration Tribunal Act 1973 (Cth), ss 7(1A), 7(1B), 7(1C), 7(2A); Remuneration and Other Legislation Amendment Act 2011 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 16A, 17A, 19, 20, 21(2)); Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 11(2) (as originally enacted); Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 1, item 6 and Sched 2, items 1, 2, 3, 5, 6, 7, 8, 9).
[5]Remuneration Tribunal Determination 2012/02, Pt 2 (cl 2.2); Remuneration Tribunal Determination 2012/03, Pt 2 (cl 2.3), Pt 3 (cl 3.1); Remuneration Tribunal Determination 2012/15, Pt 1 (cl 1.3 and cl 1.4 (insofar as it relates to cl 1.3)); Remuneration Tribunal Determination 2013/13, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1); Remuneration Tribunal Determination 2014/10, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1); Remuneration Tribunal Determination 2015/06, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1).
[6]Section 51(xxxi) provides:
"The Parliament shall, subject to this Constitution, have power to make laws for the peace, order, and good government of the Commonwealth with respect to:
…
(xxxi)the acquisition of property on just terms from any … person for any purpose in respect of which the Parliament has power to make laws".
The parliamentary allowance
Section 48 of the Constitution itself provided for an initial allowance to be paid to members of Parliament[7]. Even at Federation, payment of some kind of remuneration to members of Parliament was regarded not as a modern innovation, but as an essential aspect of democratic government[8]. During the Convention Debates, there was discussion about whether the payment was really an allowance for the reimbursement of expenses, as opposed to salary[9], but the wording of s 48 retained the general term "an allowance". The term might be thought to cover both.
[7]Section 48 provides: "Until the Parliament otherwise provides, each senator and each member of the House of Representatives shall receive an allowance of four hundred pounds a year, to be reckoned from the day on which he takes his seat." Similarly, s 66 provides: "There shall be payable to the Queen, out of the Consolidated Revenue Fund of the Commonwealth, for the salaries of the Ministers of State, an annual sum which, until the Parliament otherwise provides, shall not exceed twelve thousand pounds a year."
[8]Quick and Garran, The Annotated Constitution of the Australian Commonwealth, (1901) at 499.
[9]Official Record of the Debates of the Australasian Federal Convention, (Sydney), 2 April 1891 at 653-654.
The allowance was fixed by s 48 at a sum to be paid "[u]ntil the Parliament otherwise provides"[10]. Section 51(xxxvi)[11] contains a grant of power in respect of matters for which the Constitution makes provision "until the Parliament otherwise provides". That phrase conveys that the Commonwealth Parliament is free to legislate from time to time as may appear appropriate.
[10]Similarly, the annual sum appropriated for the payment of salaries of the Ministers of State under s 66 is also "until the Parliament otherwise provides".
[11]Section 51(xxxvi) provides:
"The Parliament shall, subject to this Constitution, have power to make laws for the peace, order, and good government of the Commonwealth with respect to:
…
(xxxvi) matters in respect of which this Constitution makes provision until the Parliament otherwise provides".
Quick and Garran[12] were of the view that neither the principle that a parliamentary allowance should be provided nor the amount of such an allowance were intended as permanent constitutional provisions and that the Commonwealth Parliament could reduce, increase or abolish the allowance. This special case does not require consideration of the exact breadth of the Parliament's powers in this regard. The provisions in question do not effect an extinguishment of the retiring allowances. It may, however, be observed that in fact the allowance provided since Federation has not always been increased by legislation and that this accords with the discretion generally given to the Parliament.
[12]Quick and Garran, The Annotated Constitution of the Australian Commonwealth, (1901) at 499.
The Parliament initially "otherwise provided" in 1907, when the allowance under s 48 was increased[13]. Since then the allowance has for the most part been increased, but it has also been reduced at certain points, such as during the Great Depression[14], evidently because of prevailing social conditions.
[13]Parliamentary Allowances Act 1907 (Cth). In respect of s 66, see Ministers of State Act 1915 (Cth).
[14]Financial Emergency Act 1931 (Cth); Financial Emergency Act 1932 (Cth).
In 1973 the Remuneration Tribunal, created under the Remuneration Tribunal Act, was given power to determine parliamentary allowances. Section 7(1) of that Act provides:
"The Tribunal shall, from time to time as provided by this Part, inquire into, and determine, the allowances (including allowances in accordance with section 48 of the Constitution) to be paid out of the public moneys of the Commonwealth to members of the Parliament by reason of their membership of the Parliament or by reason of their holding particular offices …"
It does not appear to be in dispute that s 7(1) is authorised by s 51(xxxvi) and s 48 of the Constitution, together, so far as concerns the parliamentary and associated allowances.
As the terms of s 7(1) imply, the allowances which may be the subject of a Remuneration Tribunal Determination are not limited to these allowances, which have been treated as parliamentarians' remuneration for some time. The annual parliamentary allowance is sometimes called "salary" or "basic salary", as is the Minister's salary. The Remuneration Tribunal also determines the allowances to be provided for travel, electorate, office and other expenses.
A Determination of the Remuneration Tribunal is a legislative instrument, which until 5 August 2011 was subject to disallowance by either House of Parliament[15]. Pursuant to s 7(9)(b), allowances provided for in a Determination under s 7(1) are to be paid out of Consolidated Revenue.
[15]As from 5 August 2011, the Remuneration Tribunal Act was amended by the insertion of s 7(8AA), the effect of which was to provide that Determinations were not subject to disallowance.
The retiring allowances
The same head of legislative power which supports the parliamentary allowance supports provisions of the Superannuation Act concerning benefits to retired members of Parliament[16]. However, a retiring allowance has only been payable since the passing of that Act, in 1948[17].
[16]Theophanous v The Commonwealth (2006) 225 CLR 101 at 121 [37]; [2006] HCA 18.
[17]Formerly named the Parliamentary Retiring Allowances Act 1948 (Cth).
Section 18(1) of the Superannuation Act has at all relevant times provided that:
"Subject to this Act, a member who ceases to be entitled to a parliamentary allowance shall be entitled to benefits in accordance with this section."
The benefits are to be paid by the Commonwealth[18].
[18]Parliamentary Contributory Superannuation Act 1948 (Cth), s 14A.
The principal benefit referred to in s 18(1) is a retiring allowance payable during the member's lifetime at the rate applicable according to the scale in sub‑s (6)[19]. A minimum period of service is required for eligibility for a retiring allowance. Sub-section (6) provides that the rate of retiring allowance is a percentage of the rate of parliamentary allowance "for the time being payable to a member". The percentage provided in the scale depends upon the number of years served.
[19]Parliamentary Contributory Superannuation Act 1948 (Cth), ss 18(1A), 18(1B), 18(2).
Provision is also made in the Superannuation Act for the payment of additional retiring allowances to former parliamentary office holders[20] and to former Ministers of State[21], which are calculated by reference to a percentage of the allowance or salary for the time being payable to the holder of office or Minister[22].
[20]Parliamentary Contributory Superannuation Act 1948 (Cth), s 18(9)(b).
[21]Parliamentary Contributory Superannuation Act 1948 (Cth), s18(9)(a).
[22]Parliamentary Contributory Superannuation Act 1948 (Cth), s 18(10).
Section 22T was inserted into the Superannuation Act in 1996. It is not necessary to set it out. It is common ground that its purpose was to protect retired parliamentarians who were in receipt of a retiring allowance and/or an additional retiring allowance from the effect that decreases in real terms in the rate of a parliamentary allowance, a parliamentary office holder allowance or ministerial salary would have on the rate of those retiring allowances.
The amount of benefits payable by way of retiring allowance may be reduced in certain circumstances, such as where a person entitled to a retiring allowance becomes a member of a State Parliament or a Territory Legislative Assembly[23] or where they hold an office of profit under a State or under the Commonwealth[24].
[23]Parliamentary Contributory Superannuation Act 1948 (Cth), s 21.
[24]Parliamentary Contributory Superannuation Act 1948 (Cth), s 21B.
The method of calculating the retiring allowance has changed over time. Originally the retiring allowance was fixed by s 18 as a weekly amount[25]. It is not necessary to detail all the changes but, by way of example, in some of the subsequent iterations of s 18, the retiring allowance has been fixed to a percentage of the parliamentary allowance to which a retired parliamentarian was entitled immediately before he or she became entitled to a retiring allowance, the percentage being calculated on the basis of the age of the member[26]; later the percentage was fixed on the basis of the period of parliamentary service[27].
[25]Parliamentary Retiring Allowances Act 1948 (Cth), s 18 (as enacted).
[26]Parliamentary Retiring Allowances Act 1948 (Cth), s 18 (as amended by the Parliamentary Retiring Allowances Act 1964 (Cth)).
[27]Parliamentary Retiring Allowances Act 1948 (Cth), s 18 (as amended by the Parliamentary and Judicial Retiring Allowances Act 1973 (Cth)).
The contributory nature of schemes for retirement benefits has also varied over time. When it was first passed, the Superannuation Act made provision for a Parliamentary Retiring Allowances Fund[28] out of which pensions were payable. Members of Parliament paid, by instalments, an annual sum to the Fund[29] and the Commonwealth was required to make provision for 60% of what was to be paid by way of pension[30]. This scheme ended in 1973[31].
[28]Parliamentary Retiring Allowances Act 1948 (Cth), Pt III.
[29]Parliamentary Retiring Allowances Act 1948 (Cth), s 13 (as enacted).
[30]Parliamentary Retiring Allowances Act 1948 (Cth), s 14 (as enacted).
[31]Parliamentary and Judicial Retiring Allowances Act 1973 (Cth).
The legislative scheme under which the plaintiffs were required to pay a proportion of their parliamentary and other allowances (at the rate of 11.5% for those that served less than 18 years) did not have a fund and the Commonwealth did not make contributions to it. The plaintiffs made their payments to the Commonwealth, by deduction from their allowances, and the Commonwealth paid the retiring allowances provided for by the Superannuation Act.
The changes to the retiring allowances
In 2011, the Remuneration and Other Legislation Amendment Act 2011 (Cth) amended the Superannuation Act and the Remuneration Tribunal Act. The effect of the amendments was to confer power on the Remuneration Tribunal to determine the "parliamentary base salary" of members of Parliament. The term was defined in the Remuneration Tribunal Act, as amended, as referable to the annual allowances payable for the purpose of s 48 of the Constitution and as identified in the relevant Determination as base salary. The Remuneration Tribunal Act now also provided[32] the Remuneration Tribunal with power to determine that a portion of parliamentary base salary is not "parliamentary allowance" for the purposes of the Superannuation Act. The definition of "parliamentary allowance" in the Superannuation Act was amended accordingly. Similar amendments were made in 2012 by the Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth) ("the 2012 Act") to the additional retiring allowances payable to parliamentary office holders and Ministers[33] (together with the above amendments, "the 2011/12 amendments").
[32]Remuneration Tribunal Act 1973 (Cth), s 7(1A).
[33]Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), Sched 2, items 1, 2, 5, 6.
It would appear that the purpose of these amendments is that particular allowances made to serving members, such as electorate and office allowances, which are not referable to the circumstances of retired members, should not be automatically passed on through the parliamentary allowance as a retirement benefit[34].
[34]Australia, Senate, Remuneration and Other Legislation Amendment Bill 2011, Supplementary Explanatory Memorandum at 1.

It will immediately be appreciated that there now exists the possibility that the retiring allowances could be reduced through the exercise by the Remuneration Tribunal of its powers. It is possible that the amount of parliamentary allowance for the purposes of the calculation in s 18(6) of the Superannuation Act may be reduced. Whether there is a reduction in the retiring allowance may depend on the initial determination of what is parliamentary base salary. Similarly, the amount of the parliamentary office holder allowance or ministerial salary may be reduced for the purposes of the calculations in s 18(9) and (10).
The terms of the 2011/12 amendments do not oblige the Remuneration Tribunal to fix parliamentary base salary and determine a portion which is not parliamentary allowance. In its Determinations since 2011 the Remuneration Tribunal has done so, but the Determinations have not resulted in a reduction of the retiring allowance. Although the plaintiffs contend that the amount payable was less than would have been payable before the 2011/12 amendments, they do not attempt to show how that conclusion is reached. It is, in any event, not necessary to their arguments to do so. Their point is that the rights which they previously had have been modified so that the quantum of their retiring allowances can be less than before. A question which arises is whether that to which the plaintiffs are entitled has always been subject to modification.
The Life Gold Pass
The "Life Gold Pass" has its origins in long-standing executive arrangements made between the Commonwealth and State governments for the provision of travel privileges to certain serving, and later retired, parliamentarians. The privileges have at times been controversial. Until 1976 the Life Gold Pass had no connection to statute and was supported only by Commonwealth executive powers.
In 1976 the Remuneration Tribunal enquired into, and determined, the question of parliamentary allowances under s 7(1) of the Remuneration Tribunal Act. Section 7(4)(b) provides that, if the Minister considers a further matter is significantly related to that question, the Remuneration Tribunal shall also enquire into the further matter and either determine it or report upon it. The Minister requested the Remuneration Tribunal also to enquire into the matter of the Life Gold Pass.
The Remuneration Tribunal dealt with the issue of the Life Gold Pass in Pt 2 of its Determination 1976/6, which was headed "Entitlements". Part 1 was headed "Salaries and Allowances". The Remuneration Tribunal determined that a member, on retirement from the Parliament, shall be eligible for the issue of a Life Gold Pass entitling the member to travel "at official expense" for non-commercial purposes within Australia on scheduled air, rail and motor coach and other services[35]. The number of trips which could be undertaken was not limited in any way. The period of qualification for members of the House of Representatives was stated to be 20 years or the life of seven Parliaments[36], but the entitlement to use the Pass was suspended until the member retired from Parliament[37].
[35]Remuneration Tribunal Determination 1976/6 at 18 [2.28].
[36]Remuneration Tribunal Determination 1976/6 at 18 [2.29].
[37]Remuneration Tribunal Determination 1976/6 at 19 [2.34].
Aspects of this Determination were altered by the Remuneration Tribunal at various times thereafter. In 1993 it determined that an annual cap of 25 domestic return trips should apply to those members to whom a Life Gold Pass issued on or after 1 January 1994[38].
[38]Remuneration Tribunal Determination 1993/18 at 32 [7.1].
At issue in these proceedings are the provisions made by statute in 2002 and 2012. Section 11(2) of the Members of Parliament (Life Gold Pass) Act 2002 (Cth) ("the 2002 Act") as originally enacted restricted all holders of a Life Gold Pass, other than a former Prime Minister, to a maximum of 25 domestic return trips per annum. That Act also contained a "historic shipwrecks clause"[39], which provided for compensation in the event that the Act effected an acquisition other than on just terms and such acquisition might, on that account, be invalid. The 2012 Act further amended s 11(2) to reduce the number of trips to 10[40] and bring to an end the issue of passes for members of Parliament after 6 March 2012[41].
[39]Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 32.
[40]Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), Sched 1, item 6.
[41]Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), Sched 1, item 5.
Because of the date of the fourth plaintiff's retirement in February 1990, he was not affected by the 1993 Remuneration Tribunal Determination. The extent of his use of the Life Gold Pass before the 2002 Act was therefore unlimited but it has now been restricted. In contrast, the third plaintiff retired in February 2001 and whilst his use was never unlimited it has now been restricted by the 2012 Act.
The plaintiffs' arguments
Retiring allowances
Section 51(xxxi) does not operate to protect a person's entitlement to payments under a Commonwealth statute from change. It applies only to statutes which contain provisions for the acquisition of property and it guarantees that where the Commonwealth legislates to acquire property, for a constitutionally permissible purpose, it must do so on just terms.
The question which arises from s 51(xxxi) is therefore whether the 2011/12 amendments are laws with respect to the acquisition of property. This enquiry necessitates a close analysis of the "property" which is said to have been acquired. Both enquiries – as to the rights making up the property and the character of the law changing them – require, in the first place, consideration of the nature of the entitlement to retiring allowances under the Superannuation Act.
The plaintiffs' case is that they became entitled, upon retirement, to receive a benefit, payable fortnightly during their lifetime, by way of retiring allowances. Each of the retiring allowances was defined by reference to a specified percentage of the parliamentary allowance and, where relevant, parliamentary office holder allowance and ministerial salary which was for the time being payable. The plaintiffs' statutory right, arising under the Superannuation Act, to receive money is a presently existing debt and it is therefore property. Further, the plaintiffs contend that they each have a vested chose in action to recover monies from the Commonwealth on account of the contributions made by them under the Superannuation Act.
The plaintiffs' argument then proceeds, that the 2011/12 amendments and the Determinations made thereafter effected a substantial modification to that property, by reducing the amount which might be payable by way of retiring allowances and at the same time giving a corresponding advantage to the Commonwealth. They point out that it is not necessary that property be extinguished in order to effect an acquisition. It is sufficient that a corresponding advantage, of a proprietary nature, accrues to the Commonwealth, such as where the Commonwealth's liability as a debtor is reduced.
It is no doubt correct to say that former members of Parliament could recover contributions made by them if for some reason they did not receive benefits under the Superannuation Act, for example because they did not become eligible for benefits. Section 14A of the Superannuation Act acknowledges this. The making of contributions may be regarded as a condition of eligibility for benefits under the Superannuation Act, but there the connection to what is paid by way of benefits ends. In the scheme provided for by the Superannuation Act there is no connection between the contributions made and the quantum of the benefits which are payable.
The plaintiffs' comparison of their entitlements under the Superannuation Act with a debt which is reduced, which is to say partially extinguished, implies that their entitlements have at all times been of a fixed and certain kind and that these entitlements were, to an extent, taken away. This description is apt to mislead. The 2011/12 amendments do not purport to reduce the plaintiffs' entitlements to retiring allowances. They operate to alter the method by which the quantum of the retiring allowances is calculated.
The plaintiffs do not identify when and how their rights became fixed and certain. Had they suggested that this occurred at the time they first became entitled to retiring allowances, it would seem to follow that they would not be entitled to the variations which increased the allowances, but they do not contend for this. Their argument consists principally of assertions which have no basis in the Superannuation Act or in the terms of the sections that provide the entitlement for which they claim.
The plaintiffs accept that the parliamentary allowance, on which the calculation of the retiring allowance was based before and after the 2011/12 amendments, may be either increased or decreased at any time, with the consequence that the retiring allowance can be reduced. That is because s 7(1) of the Remuneration Tribunal Act is expressed in terms such that the Remuneration Tribunal shall "from time to time" enquire into and determine parliamentary allowances. The parliamentary allowance, as the plaintiffs accept, is subject to variation. The same is true for the parliamentary office holder allowance and ministerial salary. The question is whether, having regard to the terms of the Superannuation Act, the retiring allowances stand in any different position.
Retiring allowances are, and at all relevant times have been, benefits payable "in accordance with" s 18 of the Superannuation Act and are benefits which are expressed by s 18(1) to be "[s]ubject to this Act". A reference to "this Act" clearly enough refers to the whole Act and the form which it may take from time to time[42]. Amendments which may be made to the Superannuation Act provisions respecting retiring allowances relevantly include the method of calculating the allowance. This is the answer to the plaintiffs' contention that their rights are free from any condition permitting a variation in the nature of a reduction of the value of their benefits.
[42]Ocean Road Motel Pty Ltd v Pacific Acceptance Corporation Ltd (1963) 109 CLR 276 at 280, 282-283; [1963] HCA 22; The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 74 [200]; [1998] HCA 8.
More generally the plaintiffs contend that any amendments which are made may not effect an acquisition of their property without compensation. However, their argument assumes that s 51(xxxi) applies, which is the very question that must first be addressed. It is addressed by identifying the nature of the rights making up the plaintiffs' property in order to determine whether the changes made to those rights by the 2011/12 amendments make those amendments laws "with respect to" the acquisition of property.
In Attorney-General (NT) v Chaffey[43], the statute provided that "[s]ubject to this Part" (being Pt V) and "in accordance with this Part", compensation "as is prescribed" was payable where a worker suffers injury. "Prescribed" meant prescribed by the Act or by an instrument made under the Act. At the time of the employee's injury compensation was to be calculated by reference to the "normal weekly earnings" of the employee. Amendments to the statute had the effect of excluding superannuation contributions made by the employer from the definition of "normal weekly earnings" and therefore from the calculation of compensation. In the joint judgment[44] it was said that the expressions "subject to" and "in accordance with" Pt V were naturally to be construed as identifying Pt V as amended from time to time. Their Honours went on to add that the reference to "such compensation as is prescribed" is naturally to be construed as a reference to such compensation as is prescribed from time to time. It followed that the method for quantifying the amount of compensation payable to a worker had not been fixed in any permanent form at the time the employee suffered injury and was always subject to variation.
[43](2007) 231 CLR 651; [2007] HCA 34.
[44]Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 662 [18], 663 [20].
The plaintiffs submit that the critical feature of Chaffey was not what the words "subject to this Part" conveyed about the form that the statute would take, but rather the fact that the compensation payable was to be prescribed by regulation, which may be understood to be subject to change. The submission reflects neither a fair reading of the joint judgment nor the meaning given to the term "prescribed". The point made in Chaffey was that the method by which the amount of compensation payable was derived was liable to change. That would be so regardless of the means by which the change was effected.
The term "property" in s 51(xxxi) has always attracted a liberal construction in this Court[45]. Some cases concerning s 51(xxxi) have drawn a distinction between rights recognised by the general law and those which have no existence apart from statute and whose continued existence depends upon statute[46]. The dichotomy is useful. Rights which have only a statutory basis are more liable to variation than others. As was said in Chaffey, however, where the asserted "property" has no existence apart from statute, further analysis is imperative[47]. It is a truism that statutory rights, which are not constitutionally protected, may be subject to variation or extinguished by legislative action. There are, however, some statutory rights which, having regard to their character and the context and purpose of the statute creating them, can be regarded as inherently variable. Statutory remuneration falls into that category. So too does an entitlement to a retiring allowance.
[45]The Commonwealth v New South Wales (1923) 33 CLR 1 at 20-21; [1923] HCA 34; Minister of State for the Army v Dalziel (1944) 68 CLR 261 at 276, 290; [1944] HCA 4; Bank of New South Wales v The Commonwealth (1948) 76 CLR 1 at 349; [1948] HCA 7; Telstra Corporation Ltd v The Commonwealth (2008) 234 CLR 210 at 230-231 [44]; [2008] HCA 7.
[46]Georgiadis v Australian and Overseas Telecommunications Corporation (1994) 179 CLR 297 at 305-306; [1994] HCA 6; The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 16-17 [16], 35-36 [78], 54 [140], 70 [182].
[47]Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 664 [23].
In the joint judgment in Chaffey[48] it was pointed out that it could not be said that the prospect of subsequent modification, or extinguishment, removes all statutory rights from the scope of s 51(xxxi). The question whether that provision was attracted depended upon the nature of the right. In The Commonwealth v WMC Resources Ltd[49], as in Chaffey, the right stipulated in the statute depended for its content upon the will of the legislature from time to time. The same may be said here of the provisions for calculating retiring allowances from time to time.
[48]Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 664 [24]-[25].
[49](1998) 194 CLR 1.
The plaintiffs take issue with descriptions which have been given to statutory rights of this kind, as "inherently susceptible" to modification and extinguishment[50], or "inherently unstable"[51]. They argue that such phrases should be deprecated because they are misleading and circular. All statutory provisions are liable to amendment and all are subject to s 51(xxxi), they contend.
[50]The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 38 [86]. See also Georgiadis v Australian and Overseas Telecommunications Corporation (1994) 179 CLR 297 at 305-306.
[51]The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 73 [195].
The plaintiffs' submissions overlook that these descriptions identify within particular statutory rights a feature which is critical to their nature as "property" for the purposes of the application of s 51(xxxi). If a right or entitlement was always, of its nature, liable to variation, apart from the fact that it was created by statute, a variation later effected cannot properly be described as an acquisition of property. The Commonwealth does not as a result of an amendment effecting a variation receive a release from an existing liability and therefore acquire property, as the plaintiffs contend. The Commonwealth's liability corresponds with the variation made.
The statutory right to which the plaintiffs refer was said to be subject to increase, but it was not liable to be decreased. An argument that the Commonwealth Parliament could not decrease the retiring allowances has no basis in the Superannuation Act or in s 48 of the Constitution. It would appear to accord those benefits the same status and protection as is given to the remuneration of constitutional office holders under ss 3 and 72 of the Constitution[52], but those provisions are in terms which differ from those of s 48. The plaintiffs' case, in any event, is not based upon any constitutional protection but rather upon statutory rights of a proprietary nature, and ignores the limitations inherent in those rights.
[52]For example, s 3 of the Constitution does not permit any alteration of the Governor-General's remuneration.
The 2011/12 amendments are laws which effect modifications of the plaintiffs' and others' entitlements to retiring allowances, but they are not laws with respect to the acquisition of property and s 51(xxxi) has no application to them. Given the view we have reached on the plaintiffs' arguments, it is not necessary to consider the Commonwealth's broader argument, that s 51(xxxi) does not qualify ss 48 and 51(xxxvi) as heads of power.
Life Gold Passes
The third and fourth plaintiffs argue, by analogy with their case regarding the retiring allowances, that the effect of s 7(9) of the Remuneration Tribunal Act is that, upon becoming eligible for a Life Gold Pass, a holder has a vested right to the benefits provided by the Pass and that the object and effect of the 2002 Act and the 2012 Act was to acquire those plaintiffs' property in respect of the Passes. On extinguishment of that right the Commonwealth acquired a correlative benefit of a proprietary kind.
Assuming, for present purposes, that the Remuneration Tribunal's 1976 Determination with respect to the Life Gold Pass was made under s 7(1) of the Remuneration Tribunal Act, the plaintiffs' argument would suffer from the same defects as their argument respecting the retiring allowances. Section 7(1) provides that the Remuneration Tribunal shall determine the allowances to be paid to members of Parliament "from time to time as provided by this Part", which clearly enough implies that allowances are subject to variation. Indeed the plaintiffs' arguments concerning the retiring allowances accepted that parliamentary allowances determined under s 7(1) were liable to variation, by way of increase or decrease.
It would be sufficient to dispose of the plaintiffs' arguments with respect to the Life Gold Pass for the reasons given with respect to the retiring allowances. The Commonwealth Parliament could legislate to alter the content of the right at any time. However, the plaintiffs' argument is founded upon an assumption that s 7(1) applies to the Life Gold Pass as an allowance. Something more needs to be said about the nature of a Life Gold Pass.
It appears to be common ground that s 7(1) of the Remuneration Tribunal Act was authorised by ss 48 and 51(xxxvi) of the Constitution to the extent that the Remuneration Tribunal made Determinations with respect to the Life Gold Pass. The parties appear to accept that the Determinations were made under s 7(1).

The terms of s 7(1) refer to allowances to be paid out of public monies to members of Parliament. Section 7(9) confirms that the allowances are payments of money, to be paid in accordance with the Remuneration Tribunal's Determination. A Life Gold Pass, and the privileges which attach to it, is arguably not an allowance within the meaning of these provisions.
The Remuneration Tribunal made its Determination in 1976 with respect to the matter of the Life Gold Pass following a request by the Minister under s 7(4)(b). It will be recalled that this provision allows for a further Determination by the Remuneration Tribunal of a matter which the Minister regards as "significantly related" to the principal question placed before the Tribunal, namely the parliamentary allowance and, inferentially, whether adjustments should be made to it. Questions as to the Minister's view of the relationship of a Life Gold Pass with a parliamentary allowance may be put to one side. The Determination made about the "matter" of the Life Gold Pass did not make it a Determination with respect to an allowance and the Remuneration Tribunal did not treat it in that way.
The Remuneration Tribunal dealt with the matter of the Life Gold Pass as an existing "entitlement" of some kind. The Life Gold Pass had, in fact, been provided for some time by the executive government although it was under no obligation to do so. The 1976 Determination dealt with matters of eligibility and the extent of the benefits which were to be provided under it. Whilst the Determination was no doubt intended to formalise the Life Gold Pass, to use a neutral term, it did not alter what it had always been, namely a gratuity. As such the Life Gold Pass was a privilege of a kind which was liable not only to modification, but to extinguishment.
Conclusion and orders
The questions stated for the opinion of the Court should be answered as follows:
Question One: Do any, and if so which, of the following laws and Determinations of the Remuneration Tribunal constitute or authorise an acquisition of any, and if so what, property of the plaintiffs, or any of them, otherwise than on just terms, within the meaning of s 51(xxxi) of the Constitution:
a.        Remuneration Tribunal Act 1973 (Cth), ss 7(1A), 7(1B), 7(1C) and 7(2A);
b.Remuneration and Other Legislation Amendment Act 2011 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 16A, 17A, 19, 20, 21(2));
c.Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 2, 3, 5, 6, 7, 8 and 9);
d.Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 11(2) (as originally enacted);
e.Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 1, item 6);
f.         Determination 2012/02, Pt 2 (cl 2.2);
g.        Determination 2012/03, Pt 2 (cl 2.3), Pt 3 (cl 3.1);
h.Determination 2012/15, Pt 1 (cl 1.3 and cl 1.4 (insofar as it relates to cl 1.3));
i.         Determination 2013/13, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
j.         Determination 2014/10, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
k.        Determination 2015/06, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1)?
Answer: No.
Question Two: If the answer to Question One is yes, to what, if any relief are the plaintiffs, or any of them, entitled in the proceedings?
Answer: Unnecessary to answer.
Question Three: Who should pay the costs of the proceedings?
Answer: The plaintiffs.
GAGELER J.
Constitutional context
Section 51(xxxi) of the Constitution, in providing for the Commonwealth Parliament to have power to make laws "with respect to ... the acquisition of property on just terms from any State or person for any purpose in respect of which the Parliament has power to make laws", subjects the power of the Parliament to make any law "with respect to ... the acquisition of property" for any legislative purpose to the condition that the acquisition occur only "on just terms". The just terms condition was "included to prevent arbitrary exercises of the power" at the expense of the State or individual[53] and guarantees to an individual that any law answering the description of a law with respect to the acquisition of his or her property contains provisions ensuring that the acquisition is on terms amounting to "a true attempt to provide fair and just standards of compensating or rehabilitating the individual considered as an owner of property, fair and just as between him and the government of the country"[54].
[53]Grace Brothers Pty Ltd v The Commonwealth (1946) 72 CLR 269 at 291; [1946] HCA 11.
[54]Grace Brothers Pty Ltd v The Commonwealth (1946) 72 CLR 269 at 290.
To answer the description of a law with respect to the acquisition of property within the meaning of s 51(xxxi), a law must meet two basic conditions. First, the law must authorise or effect an acquisition of property: the law must provide for the taking of property from a person and for the conferral of a corresponding interest in property on the Commonwealth or on another person[55]. Second, that acquisition of property must fit within the conception of an acquisition that can be on just terms: the acquisition must be of a nature that is consistent or congruent with provision of compensation or rehabilitation to the former owner[56].
[55]The Commonwealth v Tasmania (The Tasmanian Dam Case) (1983) 158 CLR 1 at 145; [1983] HCA 21; Australian Tape Manufacturers Association Ltd v The Commonwealth (1993) 176 CLR 480 at 499-500; [1993] HCA 10; JT International SA v The Commonwealth (2012) 250 CLR 1 at 33-34 [42], 53 [118], 68 [169], 99 [278], 130-131 [365]; [2012] HCA 43.
[56]Theophanous v The Commonwealth (2006) 225 CLR 101 at 124-126 [56]-[60]; [2006] HCA 18.
Whether a law meets those two conditions is a question of substance which can involve considerations of degree. Whether a legislative alteration of a right of property takes property from one person and confers a corresponding interest in property on another person, so as to constitute an acquisition of property, turns in part on the characteristics of the right and in part on the extent of the alteration[57]. Whether a legislative acquisition of property is congruent with provision of compensation or rehabilitation to the former owner turns on whether acquisition without compensating or rehabilitating the former owner is a necessary or characteristic feature of legislatively chosen means that are appropriate and adapted to achieving some other objective within power[58].
[57]Smith v ANL Ltd (2000) 204 CLR 493 at 504-506 [22]-[23]; [2008] HCA 58; Telstra Corporation Ltd v The Commonwealth (2008) 234 CLR 210 at 233-234 [52]; [2008] HCA 7; JT International SA v The Commonwealth (2012) 250 CLR 1 at 54-64 [119]-[154].
[58]Airservices Australiav Canadian Airlines International Ltd (1999) 202 CLR 133 at 180-181 [98]-[99]; [1999] HCA 62, applying Mutual Pools & Staff Pty Ltd v The Commonwealth (1994) 179 CLR 155 at 179-180; [1994] HCA 9.
If those two conditions are met, a law may still not answer the description of a law with respect to the acquisition of property. There remains an ultimate question of characterisation. For example, the law may fail to meet that description because the acquisition of property for which the law provides is no more than incidental to or consequential upon the law's adjustment of competing rights, claims or obligations of persons in a particular relationship or area of activity[59]. No universal discriminant has emerged to guide that ultimate question of characterisation, and perhaps none can be expected.
[59]Nintendo Co Ltd v Centronics Systems Pty Ltd (1994) 181 CLR 134 at 161; [1994] HCA 27.
Where a law does answer the description of a law with respect to the acquisition of property, however, enactment of the law will be beyond the power of the Parliament unless the law complies with the just terms condition. That is because, "by an implication required to make the condition of just terms effective", s 51(xxxi) "abstracts the power to support a law for the compulsory acquisition of property from any other legislative power"[60]. The operative principle of interpretation is that[61]:
"when you have, as you do in par (xxxi), an express power, subject to a safeguard, restriction or qualification, to legislate on a particular subject or to a particular effect, it is in accordance with the soundest principles of interpretation to treat that as inconsistent with any construction of other powers conferred in the context which would mean that they included the same subject or produced the same effect and so authorized the same kind of legislation but without the safeguard, restriction or qualification."
[60]Mutual Pools & Staff Pty Ltd v The Commonwealth (1994) 179 CLR 155 at 177.
[61]Attorney-General (Cth) v Schmidt (1961) 105 CLR 361 at 371-372; [1961] HCA 21. See also Bourke v State Bank of New South Wales (1990) 170 CLR 276 at 285-286; [1990] HCA 29.
Applied to s 51(xxxi), that principle of interpretation fits both the inherently expansive nature of a constitutional power to acquire property and the purposes served by its separate and qualified conferral. According to settled understanding[62]:
"[Section] 51(xxxi) is not to be confined pedantically to the taking of title by the Commonwealth to some specific estate or interest in land recognized at law or in equity and to some specific form of property in a chattel or chose in action similarly recognized, but that it extends to innominate and anomalous interests and includes the assumption and indefinite continuance of exclusive possession and control for the purposes of the Commonwealth of any subject of property. Section 51(xxxi) serves a double purpose. It provides the Commonwealth Parliament with a legislative power of acquiring property: at the same time as a condition upon the exercise of the power it provides the individual or the State, affected with a protection against governmental interferences with his proprietary rights without just recompense. In both aspects consistency with the principles upon which constitutional provisions are interpreted and applied demands that the paragraph should be given as full and flexible an operation as will cover the objects it was designed to effect. Moreover, when a constitution undertakes to forbid or restrain some legislative course, there can be no prohibition to which it is more proper to apply the principle embodied in the maxim quando aliquid prohibetur, prohibetur et omne per quod devenitur ad illud. In requiring just terms s 51(xxxi) fetters the legislative power by forbidding laws with respect to acquisition on any terms that are not just."
[62]Bank of NSW v The Commonwealth (1948) 76 CLR 1 at 349-350; [1948] HCA 7; ICM Agriculture Pty Ltd v The Commonwealth (2009) 240 CLR 140 at 197 [134]; [2009] HCA 51.
Section 51(xxxi)'s abstraction of power in that way qualifies the generality of the principle that the "power to make laws includes a power to unmake them" and that "the powers conferred on the Parliament under s 51 extend to the repeal, in part or in whole, of what the Parliament has validly enacted"[63]. The Parliament has ample power to create rights of property in the exercise of other grants of legislative power. But the power of the Parliament to acquire property that it has created in the exercise of another grant of legislative power is confined to s 51(xxxi).
[63]Kartinyeri v The Commonwealth (1998) 195 CLR 337 at 355 [13]; [1998] HCA 22.
That scope for another grant of legislative power to support a law for the creation of property, but not the acquisition of property within the scope of s 51(xxxi), applies to the power granted by s 51(xxxvi) to make laws with respect to parliamentary allowances and ministerial salaries, for which interim provision was made in ss 48 and 66 of the Constitution, as much as it applies to the other grants in s 51 and s 52 of the Constitution. Each is granted as a plenary legislative power but each is expressly granted "subject to this Constitution".
Where the Parliament exercises a legislative power to create a statutory right in the nature of property, attention to the particular statutory characteristics of that statutory right is needed in order to determine whether a subsequent legislative alteration of the right meets the threshold condition of a law with respect to the acquisition of property – that the law provide for the taking of property and for the conferral of a corresponding interest in property[64]. The statutory characteristics of a statutory right of property cannot be assumed to mimic the characteristics of a common law right of property[65]. The statutory characteristics of the right must also be taken in their totality. Unless the statute itself allows the person to pick and choose, the person on whom a statutory right is conferred cannot take the benefit of some characteristics of the right and deny the burden of others[66].
[64]Eg Telstra Corporation Ltd v The Commonwealth (2008) 234 CLR 210 at 232 [49].
[65]Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 665 [26]-[27]; [2007] HCA 34.
[66]Phonographic Performance Co of Australia Ltd v The Commonwealth (2012) 246 CLR 561 at 571 [10], 577 [36], 583 [63], 598-599 [129]; [2012] HCA 8.
One potential characteristic of a statutory right of property created in the exercise of another grant of legislative power is that the right may be created on terms which make that right susceptible to administrative or legislative alteration or extinguishment without acquisition. That is to say, susceptibility to alteration or extinguishment by subsequent administrative or legislative action might be a characteristic of the right that is created – "inherent at the time of its creation and integral to the property itself"[67]. Whether, and if so to what extent, a right of property created in the exercise of another grant of legislative power is inherently susceptible to administrative or legislative alteration or extinguishment necessarily turns on the construction of the legislation creating that right: on its text, read in its total context and in a manner which best achieves its legislative purpose or object.
[67]Minister for Primary Industry and Energy v Davey (1993) 47 FCR 151 at 165.
Legislatively created rights in the nature of accrued entitlements to payments from consolidated revenue have been recognised to be rights of property[68]. Their legislative alteration, if to the financial benefit of the Commonwealth or another person, may amount to an acquisition of property[69]. Legislatively created rights of that nature have nevertheless been said to be proprietary rights of a kind "which, as a general rule, are inherently susceptible of variation"[70]. That general rule can be no more than a presumption of legislative intention which informs the construction of statutes by which such rights are created. The strength of the presumption must vary with the context. The presumption is undoubtedly strong in relation to rights to receive pensions, allowances and benefits in the nature of social welfare payments, which can be regarded as having been conferred from the outset on the basis that they might be redistributed or withdrawn at any time[71]. The presumption can apply at best weakly in relation to accrued entitlements to receive payments which can properly be regarded as having formed part of a package of remuneration for services rendered.
[68]Health Insurance Commission v Peverill (1994) 179 CLR 226 at 235; [1994] HCA 8.
[69]Health Insurance Commission v Peverill (1994) 179 CLR 226 at 236.
[70]Health Insurance Commission v Peverill (1994) 179 CLR 226 at 237.
[71]Cf United States v Teller 107 US 64 at 68 (1882) and Lynch v United States 292 US 571 at 577 (1934), quoted in Health Insurance Commission v Peverill (1994) 179 CLR 226 at 262.
The textual significance of a particular statutory right being conferred "subject to" the whole or some part of the legislation which created that right must also vary with the statutory context. The words are commonly taken to extend to the legislation as originally enacted and as later amended from time to time[72]. But the words do not speak directly to the source of the power to amend, and they do not necessarily connote a lack of permanence in the statutory right created. Appearing in patents legislation[73] or copyright legislation[74], for example, the words are less suggestive of the inherent susceptibility of statutory rights to subsequent legislative alteration than are the same words appearing in workers' compensation legislation[75] or in legislation creating and extending exclusive rights to explore for petroleum in an area of the continental shelf which at the time of creation and extension of those rights was subject to competing claims of sovereign rights in international law[76].
[72]Ocean Road Motel Pty Ltd v Pacific Acceptance Corporation Ltd (1963) 109 CLR 276 at 280, 282-283; [1963] HCA 22.
[73]Eg Patents Act 1990 (Cth), s 13. See Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 664 [24].
[74]Eg Copyright Act 1968 (Cth), ss 32, 89-92. See The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 70 [182]; [1998] HCA 8.
[75]Eg Work Health Act 1986 (NT), s 53. See Attorney-General (NT) v Chaffey (2007) 231 CLR 651 at 662 [18], 665-666 [30].
[76]Eg Petroleum (Submerged Lands) Act 1967 (Cth), ss 5(8) and 28. See The Commonwealth v WMC Resources Ltd (1998) 194 CLR 1 at 73-75 [198]-[203].
Even where those words can be read as signifying that a characteristic of a statutory right is that the right is susceptible to some future legislative alteration, they cannot necessarily be read as signifying that the right is susceptible to any and all legislative alteration, no matter how extreme the alteration and irrespective of the purpose of the alteration. In Attorney-General (NT) v Chaffey, reliance was placed on workers' compensation entitlements being conferred "subject to" an identified part of workers' compensation legislation to hold that accrued rights "were of a nature which rendered them liable to variation by a provision such as that made" in a particular amendment the purpose and effect of which was limited to restoring entitlements to levels understood before a recent court decision. Yet a note of caution was sounded when it was added that "subsequent legislation might so remove the content of rights to compensation, as to go beyond what was contemplated ... and amount to abolition"[77].
[77](2007) 231 CLR 651 at 665-666 [30]-[31].
All of this supports the view expressed by Gleeson CJ in Theophanous v The Commonwealth that it is for the Parliament in the exercise of power conferred by s 51(xxxvi) to decide the form and incidents of schemes for the provision of allowances (including retirement allowances in the nature of superannuation or pension entitlements) to parliamentarians, that it is open to the Parliament in the exercise of that power to create rights the statutory modification or extinguishment of which could amount to an acquisition of property within the meaning of s 51(xxxi) and that "[w]hether or not s 51(xxxi) has potential application to such modification or extinguishment may depend upon the legislative context in which such modification or extinguishment occurs". His Honour rejected the proposition that "statutory superannuation or pension benefits are inherently defeasible and that, on that account alone, their modification or withdrawal could never constitute an acquisition of property"[78].
[78](2006) 225 CLR 101 at 113-114 [7].

That view of the operation and interaction of ss 51(xxxvi) and 51(xxxi), although tentatively expressed by Gleeson CJ in Theophanous, is one which I accept without qualification. It provides the starting point for consideration of the arguments in this special case.
Special case
The plaintiffs are former parliamentarians, and are also former Ministers or former parliamentary office holders or both. They retired from the Parliament between 1990 and 2001. Their complaint is about alterations made by the Parliament after their retirement to entitlements to payments from the Consolidated Revenue Fund for which they qualified at the time of their retirement under legislation enacted under s 51(xxxvi).
The plaintiffs argue that an acquisition of their property otherwise than on just terms has resulted from alterations made by the Parliament in 2011 and 2012 to their statutory rights to receive "retiring allowance". Two of the plaintiffs, the Honourable John Moore AO and the Honourable Barry Cohen AM, separately argue that alterations made by the Parliament in 2002 and 2012 to their statutory rights as holders of Life Gold Passes to travel within Australia for non-commercial purposes at Commonwealth expense resulted in acquisitions of their property otherwise than on just terms.
For reasons which follow, I reject the argument that property has been acquired by the alterations to the plaintiffs' statutory rights to receive retiring allowance but accept the arguments of Mr Moore and Mr Cohen that property has been acquired by the alterations to their statutory rights as holders of Life Gold Passes.
Retiring allowance
The plaintiffs' rights to receive retiring allowance have at all relevant times been conferred by the Parliamentary Contributory Superannuation Act 1948 (Cth) ("the Superannuation Act"). The alterations of rights of which they complain were brought about by the Remuneration and Other Legislation Amendment Act 2011 (Cth) ("the 2011 Act") and the Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth) ("the 2012 Act"). Evaluation of their arguments that the 2011 Act and the 2012 Act resulted in an acquisition of property requires an examination of precisely what their rights had previously been and precisely how those rights were altered.
Uncluttering the requisite analysis as much as possible, it is enough to look to the rights which all of the plaintiffs had to receive retiring allowance as former parliamentarians immediately before the commencement of the 2011 Act, and to the operation of the 2011 Act in relation to those rights. The plaintiffs also then had rights to receive additional retiring allowance as former Ministers or former holders of parliamentary office or both. The 2012 Act came to operate in relation to those additional rights. The operation of the 2012 Act in relation to additional retiring allowance is no different in principle, however, from the operation of the 2011 Act in relation to retiring allowance. For that reason, additional retiring allowance and the operation of the 2012 Act can both be put to one side.
The content of the right of a former parliamentarian to receive retiring allowance under the Superannuation Act immediately before the commencement of the 2011 Act needs to be understood against the background of rights then conferred on current parliamentarians through the combined operation of the Remuneration Tribunal Act 1973 (Cth) ("the Remuneration Tribunal Act"), the Remuneration and Allowances Act 1990 (Cth) ("the Remuneration and Allowances Act") and the Parliamentary Entitlements Act 1990 (Cth) ("the Parliamentary Entitlements Act") as in force at that time.
The Remuneration and Allowances Act and the Parliamentary Entitlements Act were enacted shortly after Brown v West, where this Court observed[79]:
"Apart from the possible operation of s 48, it may be that our Constitution provides such a separation of powers as would preclude any exercise of the executive power which takes the form of the discretionary conferring of benefits having a pecuniary value on individual members of the Parliament, not being mere facilities for the functioning of Parliament."
The three Acts together operated to ensure that payments from the Consolidated Revenue Fund to or for the benefit of current parliamentarians occurred with specific statutory authority.
[79](1990) 169 CLR 195 at 202; [1990] HCA 7.
The centrally relevant provision of the Remuneration Tribunal Act was s 7. Section 7(1) provided that the Remuneration Tribunal "shall, from time to time ... inquire into, and determine, the allowances (including allowances in accordance with section 48 of the Constitution) to be paid out of the public moneys of the Commonwealth to members of the Parliament by reason of their membership of the Parliament". The term "allowance" was defined in s 3(1) to include but not be limited to "an annual allowance and a travelling allowance". Section 7(4) made additional provision for the Tribunal to inquire into and determine any matter which the Tribunal or the Minister considered to be significantly related to a matter into which the Tribunal inquired under s 7(1). Under s 7(9)(b), notwithstanding the provisions of any other law, an allowance to which a subsisting determination applied was to be paid in accordance with the determination out of the Consolidated Revenue Fund. Section 8(1) provided for determinations under s 7(1) to be made at intervals of not more than one year.
The Remuneration and Allowances Act provided, by force of s 6, for a current member to be entitled to receive three principal forms of allowance referred to in Sched 3. The first was an allowance by way of salary referred to in cl 1 of Sched 3. The second was an electorate allowance referred to in cl 2 of Sched 3. The third was another allowance of a kind to which reference was made in cl 3 of Sched 3. Those other allowances relevantly included an overseas study allowance (entitling the member to financial assistance for overseas study travel while remaining a member) as well as an entitlement to receive on retirement a Life Gold Pass.
The allowance by way of salary referred to in cl 1 of Sched 3 was specified in that clause to be an annual allowance and to be equal to either the minimum annual rate of a salary payable to a Commonwealth employee holding a designated classification under the Public Service Act 1999 (Cth) or a prescribed percentage of a reference salary set by regulation. Immediately before the commencement of the 2011 Act, the allowance by way of salary was in fact set by regulation as a prescribed percentage of a public service reference salary commonly referred to as Reference Salary A[80].
[80]Remuneration and Allowances Regulations 2005 (Cth).
By force of s 3(2) of the Remuneration and Allowances Act, a determination made by the Remuneration Tribunal which was inconsistent with a provision of that Act operated in substitution for that provision. The result in practice was that the Remuneration Tribunal made annual determinations of electorate allowance and other allowances, including overseas study allowance, which substituted for the electorate and other allowances referred to in cll 2 and 3 of Sched 3.
However, s 3(2) of the Remuneration and Allowances Act created an exception for cl 1 of Sched 3. Being a later and specific enactment, the exception also operated as an exception to the generality of s 7(9)(b) of the Remuneration Tribunal Act. The result of that exception was that the Remuneration Tribunal had no power to make a determination which had the effect of altering the allowance by way of salary for a member as then set by regulation as a prescribed percentage of Reference Salary A.
The Parliamentary Entitlements Act supplemented the Remuneration and Allowances Act by providing in s 5(1) for members to be entitled to additional benefits determined by the Remuneration Tribunal under s 7 of the Remuneration Tribunal Act. Those other benefits were confined by s 5(2) to benefits not in the nature of remuneration.
Against that background, s 18(1) of the Superannuation Act as then in force provided that "[s]ubject to this Act, a member who ceases to be entitled to a parliamentary allowance shall be entitled to benefits in accordance with this section". Section 18(6) provided for the rate of retiring allowance payable to a former member to be a specified percentage (varying with years of service) of "the rate of parliamentary allowance for the time being payable to a member". Section 14A provided that the Commonwealth was to make payments in respect of benefits provided for by the Act, and s 27 provided that those payments were to be made out of the Consolidated Revenue Fund, which was appropriated accordingly.
Importantly, the rate of retiring allowance payable to a former member in accordance with s 18(6) was affected by s 22T of the Superannuation Act. Section 22T was expressed to apply in the event of a decrease in the rate of parliamentary allowance payable to a current member. In that event, the section operated to require the retiring allowance payable to a former member to be calculated on the basis that the rate of parliamentary allowance for the time being payable to a current member was the earlier, higher rate of parliamentary allowance. The section went on to require retiring allowance to continue to be calculated on the basis of that earlier, higher rate until such time as parliamentary allowance payable to a current member increased to at least the earlier rate.
Section 22T of the Superannuation Act in that way set a floor on the amount of retiring allowance payable to a former member. The amount of retiring allowance could always go up. But the amount of retiring allowance could never go down, even if the parliamentary allowance for the time being payable to current members went down.
The Superannuation Act defined "parliamentary allowance" in s 4(1) relevantly to mean "an allowance by way of salary" under cl 1 of Sched 3 to the Remuneration and Allowances Act[81]. The practical effect of that definition was to require the retiring allowance of a former member under s 18(1) to be calculated under s 18(6) as a specified percentage of Reference Salary A. The entitlement of a current member to electorate allowance or to another allowance such as overseas study travel, or to any other benefit not in the nature of remuneration, did not enter into the calculation.
[81]Section 4(1), "parliamentary allowance", par (c).
The 2011 Act had as its main purpose amending the Remuneration and Allowances Act to implement recommendations of a report of the Committee for the Review of Parliamentary Entitlements in 2010 concerning the allowances of current and former parliamentarians[82]. The principal recommendations of the Committee were relevantly to the effect that the notion of a reference salary should be abandoned, that the Remuneration Tribunal should have power to determine a base salary for parliamentarians on the basis of the Tribunal's assessment of the value of their work as parliamentarians, and that the Tribunal's power should extend to allowing the Tribunal to dispense with electorate allowance and the allowance for overseas study travel and to fold the value of those existing allowances into its determination of parliamentary base salary[83]. A subsidiary recommendation of the Committee was to the effect that preventative measures should be taken to ensure that folding the value of electorate allowance and overseas study travel into the parliamentary base salary of current members did not have the unintended consequence of increasing the value of the retiring allowance payable to former parliamentarians under the Superannuation Act[84].
[82]Committee for the Review of Parliamentary Entitlements, Review of Parliamentary Entitlements, (2010).
[83]Committee for the Review of Parliamentary Entitlements, Review of Parliamentary Entitlements, (2010) at 58-60, 84-85.
[84]Committee for the Review of Parliamentary Entitlements, Review of Parliamentary Entitlements, (2010) at 60-61.
The 2011 Act implemented the principal recommendations of the Committee by the simple expedient of repealing cl 1 of Sched 3 to the Remuneration and Allowances Act and amending s 3(2) to delete the exception. Henceforth, a determination of the Remuneration Tribunal was to operate in accordance with its terms in spite of any provision of the Remuneration and Allowances Act.
The 2011 Act went on to implement the subsidiary recommendation of the Committee. It did so in part by amending the definition of "parliamentary allowance" in the Superannuation Act to substitute for part of the existing definition a new definition to the effect that "parliamentary allowance means ... parliamentary base salary (within the meaning of the [Remuneration Tribunal Act]), less any portion determined under subsection 7(1A) of [the Remuneration Tribunal Act]"[85].
[85]Parliamentary Contributory Superannuation Act 1948 (Cth), s 4(1), "parliamentary allowance", par (d) (as in force on 5 August 2011).
Complementing that amendment to the definition in the Superannuation Act, the 2011 Act made two relevant amendments to the Remuneration Tribunal Act. One was to insert a definition of "parliamentary base salary", which was to mean so much of the allowances determined under s 7(1) as "represents the annual allowance payable for the purposes of section 48 of the Constitution" and "is identified in the determination as base salary". The other was to insert a new s 7(1A) to provide that "[t]he Tribunal may determine that a portion of parliamentary base salary is not parliamentary allowance for the purposes of the [Superannuation Act]".
After the 2011 Act, the amount of retiring allowance to which a former member was entitled under s 18(1) of the Superannuation Act therefore remained that calculated under s 18(6) as a specified percentage of parliamentary allowance as defined in s 4(1). The calculation required by s 18(6) continued to be constrained by s 22T, so that the amount of retiring allowance could always go up if parliamentary allowance went up but could never go down if parliamentary allowance went down.
What the 2011 Act changed was how parliamentary allowance was defined for the purpose of the Superannuation Act in s 4(1) of that latter Act. Gone was the old definition which indirectly tied parliamentary allowance to Reference Salary A. In its place was a new definition which tied parliamentary allowance for the purpose of the Superannuation Act to such amount as the Remuneration Tribunal might determine under s 7(1) of the Remuneration Tribunal Act to be the parliamentary base salary payable to a current parliamentarian less such proportion as the Tribunal might under s 7(1A) determine not to be parliamentary allowance for the purposes of the Superannuation Act.
Examination of the practical outworking of that change is instructive. Immediately before the commencement of the 2011 Act, the amount of parliamentary allowance, tied to Reference Salary A, was $140,910. In the first half of 2012, the then current value of Reference Salary A was $146,380. The Remuneration Tribunal in March 2012[86] determined parliamentary base salary to be $185,000 and determined the portion of parliamentary base salary that was not parliamentary allowance for the purposes of the Superannuation Act to be $38,620, being the difference between the then current value of Reference Salary A and the amount the Tribunal then determined to be parliamentary base salary. The amount of parliamentary allowance for the purpose of the Superannuation Act was accordingly $146,380. Around the middle of 2012, the value of Reference Salary A rose to $150,780 and the Tribunal determined parliamentary base salary and the portion that was not parliamentary allowance for the purposes of the Superannuation Act in a way that increased parliamentary allowance to $150,780[87].
[86]Remuneration Tribunal Determination 2012/02.
[87]Remuneration Tribunal Determination 2012/15.
In 2013[88], the Remuneration Tribunal determined parliamentary base salary by increasing the parliamentary base salary it had determined in the middle of 2012 by a specified percentage and determined the portion that was not parliamentary allowance for the purposes of the Superannuation Act in a way that increased parliamentary allowance for the purposes of the Superannuation Act by the same percentage. Subsequent determinations of the Tribunal left the amounts of parliamentary base salary and of parliamentary allowance for the purposes of the Superannuation Act in 2014 and 2015 at the rates which had been determined in 2013[89].
[88]Remuneration Tribunal Determination 2013/13.
[89]Remuneration Tribunal Determinations 2014/10 and 2015/06.
The retiring allowance of former parliamentarians has in that way remained in practice linked to Reference Salary A as it was in 2012, increased in 2013 by the same percentage as parliamentary base salary then increased.
Significantly, the plaintiffs do not challenge the amendment to the definition of parliamentary allowance in the Superannuation Act. They seek to benefit from it. They want to take advantage of the inflating aspect of the new definition, which fastens on a determination of parliamentary base salary under s 7(1) of the Remuneration Tribunal Act. At the same time, they deny the validity of the deflating aspect of the new definition, which under s 7(1A) of the Remuneration Tribunal Act excludes a portion of parliamentary base salary from parliamentary allowance for the purpose of the Superannuation Act. Section 7(1A) of the Remuneration Tribunal Act alone, they argue, is invalid as an acquisition of their statutory property other than on just terms.
According to the plaintiffs, the Tribunal's determinations in 2012, 2013, 2014 and 2015 validly determined parliamentary base salary in the exercise of the power conferred by s 7(1) of the Remuneration Tribunal Act, but were invalid insofar as they reduced parliamentary allowance in the purported exercise of the power conferred by s 7(1A) of the Remuneration Tribunal Act for the purpose of the Superannuation Act to a level below parliamentary base salary. For example, the plaintiffs say that in 2012 the amount of parliamentary allowance validly determined by the Tribunal for the purpose of the Superannuation Act was not $146,380 but $185,000. They say that they were entitled to receive retiring allowance calculated by reference to that higher amount.
What is apparent is that the plaintiffs have not in fact received an amount of retiring allowance as a result of the 2011 Act which is less than they received before the 2011 Act. The amount of retiring allowance they have received since the 2011 Act has increased.
What is also apparent is that the plaintiffs in their argument approbate and reprobate. They seek to take the benefit of the new definition of parliamentary allowance in the Superannuation Act. Yet they seek to shear away a qualification intrinsic to that new definition.
The fundamental problem with the plaintiffs' argument is that it is founded on too large and imprecise a conception of just what their statutory rights to retiring allowance had been before the enactment of the 2011 Act. The plaintiffs did not then have rights to be paid a percentage of whatever might be capable of being regarded from time to time as the base salary of a current parliamentarian. Their rights under ss 18(1) and 18(6) of the Superannuation Act were confined to rights to be paid a percentage of parliamentary allowance as then defined in s 4(1). That definition admitted of the rate of parliamentary allowance being varied up or down at any time by regulation made for the purpose of cl 1 of Sched 3 to the Remuneration and Allowances Act. The plaintiffs at the same time had the protection of s 22T of the Superannuation Act preventing the amount they were entitled to from being reduced.

From 1974 to 1990, several determinations by the Remuneration Tribunal made under the RT Act were disapproved by a single House of the Parliament under s 7(8) of the RT Act. For example: 1974 Determinations (including salaries and allowances payable to parliamentarians) were disapproved by the Senate on 25 July 1974; August 1975 Determinations (including salaries and allowances payable to parliamentarians) were disapproved by the Senate on 9 September 1975; Determination 1978/7 (office holder additional allowances and salaries) was disapproved by the House of Representatives on 17 August 1978; and Determinations 1990/13 (basic salary) and 1990/15 (office holder additional allowances and salary) were disapproved by the House of Representatives on 31 May 1990.
Then, from 20 June 1990 to 5 February 2001 (the date Mr Moore ceased to be a parliamentarian), Parliament "otherwise provided" for the payment of parliamentary allowances to parliamentarians and certain parliamentary office holders pursuant to cl 1 of Sched 3 to the 1990 Allowances Act[232], s 7 of the RT Act and determinations made by the Remuneration Tribunal under the RT Act. The operation of the 1990 Allowances Act, the RT Act and determinations made pursuant to the RT Act was modified by legislation from time to time, insofar as those Acts pertained to the provision of parliamentary allowances[233].
(ii) Ministerial salaries
[232]See [297] above.
[233]See, eg, Sched 2 to the Industrial Relations Legislation Amendment Act (No 2) 1994 (Cth); [297]-[299] above.
Parliament has "otherwise provided", pursuant to ss 66 and 51(xxxvi), for the appropriation of monies for the payment of ministerial salaries since at least the enactment of the Ministers of State Act 1915 (Cth).
The annual sum appropriated for ministerial salaries was increased by the Ministers of State Act 1917 (Cth). It was then reduced twice – by the 1931 Emergency Act and the 1932 Emergency Act – before being returned to close to the 1915 position by the Ministers of State Act 1935 (Cth).
Since 1952, the Parliament has "otherwise provided" for the annual appropriation for ministerial salaries by the Ministers of State Act 1952 (Cth). That Act has been amended on several occasions[234]. The Remuneration Tribunal enquires into and reports on ministerial salaries[235], but does not determine the specific amounts payable to each Minister.
(iii) Review of parliamentary allowances, retiring allowances and LGP
[234]See, eg, Ministers of State Act 1956 (Cth); Ministers of State Act 1959 (Cth); Ministers of State Act 1964 (Cth).
[235]See s 6(1) of the RT Act. See, eg, Remuneration Tribunal, Report Number 1 of 2015: Report on Ministers of State – Salaries Additional to the Basic Parliamentary Salary, (2015).
The appropriate nature and amount of parliamentary allowance and retiring allowance and the appropriate nature and extent of the provision of a LGP have been the subject of repeated review and consideration[236]. For present purposes, it is sufficient to refer to the Committee for the Review of Parliamentary Entitlements, Review of Parliamentary Entitlements, (2010) ("the Belcher Review").
[236]See, eg, Report of the Committee of Enquiry into the Salaries and Allowances of Members of the National Parliament, (1952); Report of the Committee of Inquiry into the Salaries and Allowances of Members of the Commonwealth Parliament, (1955); Commonwealth Actuary, Parliamentary Retiring Allowances Fund, (1957); Report of the Committee of Inquiry into the Salaries and Allowances of Members of the Commonwealth Parliament, (1959); Report by the Commonwealth Actuary upon the Parliamentary Retiring Allowances Fund, (1959); Salaries and Allowances of Members of the Parliament of the Commonwealth: Report of Inquiry by Mr Justice Kerr, (1971); Remuneration Tribunal, 1976 Review: Statement, (1976); Remuneration Tribunal, 1988 Review, (1988); Remuneration Tribunal, 1993 Review, (1993); Senate Select Committee on Superannuation, The Parliamentary Contributory Superannuation Scheme & the Judges' Pension Scheme, (1997); Australian National Audit Office, Administration of Parliamentarians' Entitlements by the Department of Finance and Deregulation, (2009).
The Belcher Review concluded that the then existing arrangements for parliamentary entitlements were an extraordinarily complex mix of primary legislation, regulations, determinations, procedural rules, executive decisions, accepted conventions and administrative practices resulting in inconsistency, ambiguity, duplication, overlap, redundancy and gaps in the framework. The Belcher Review recommended "a simplified, transparent and accountable framework that has regard to contemporary community standards"[237].
[237]Belcher Review at 8.
The Belcher Review recommended, amongst other things, that:
(1)Parliament restore the power of the Remuneration Tribunal to determine parliamentary base salary and remove the Parliament's ability to disallow determinations made by the Remuneration Tribunal[238];
(2)all salary matters should be determined independently by the Remuneration Tribunal following a work value assessment and that the level of parliamentary remuneration would be more transparent if all allowances providing a personal benefit, such as electorate allowance and overseas study travel entitlement, were considered to be part of the salary[239];
(3)the LGP scheme be abolished prospectively so that it would not be available to those who entered Parliament at or after the next federal election and, for existing LGP holders, the LGP scheme be reduced from 25 to 10 free domestic return trips per year[240].
[238]Belcher Review at 12, 50-51, Recommendation 1.
[239]Belcher Review at 13, 59-60, Recommendation 6.
[240]Belcher Review at 17, 83, Recommendation 20.
If these recommendations were adopted, then the Belcher Review further recommended that the Parliament "take preventative measures so that the folding in of electorate allowance does not flow to the retirement benefits of members of the parliamentary contributory superannuation scheme" under the Superannuation Act[241].
[241]Belcher Review at 60-61, Recommendation 7; see also at 13.
The changes to the calculation of retiring allowance caused by the 2011 Amendment Act and the 2012 LGP Act (namely, the RT Impugned Provisions and Determinations) were the direct result of those recommendations by the Belcher Review[242] and subsequently the Remuneration Tribunal[243].
[242]For the 2011 Amendment Act, see Australia, House of Representatives, Remuneration and Other Legislation Amendment Bill 2011, Explanatory Memorandum at 2, 9; Australia, Senate, Remuneration and Other Legislation Amendment Bill 2011, Supplementary Explanatory Memorandum; Australia, House of Representatives, Parliamentary Debates (Hansard), 24 March 2011 at 3156-3158. For the 2012 LGP Act, see Australia, House of Representatives, Members of Parliament (Life Gold Pass) and Other Legislation Amendment Bill 2012, Explanatory Memorandum at 1; Australia, House of Representatives, Parliamentary Debates (Hansard), 9 February 2012 at 556.
[243]See Australia, House of Representatives, Members of Parliament (Life Gold Pass) and Other Legislation Amendment Bill 2012, Explanatory Memorandum at 1.
No infringement of s 51(xxxi)
The plaintiffs' challenge to the RT Impugned Provisions and Determinations concerned the validity of legislative provisions (and associated Remuneration Tribunal determinations) that had the effect of calculating the rate of retiring allowance by reference to an amount potentially less than the amounts payable to serving parliamentarians, parliamentary office holders and Ministers from time to time.
But, as the Commonwealth submitted, at the time when they became eligible to receive a retiring allowance, each plaintiff could do no more than say that his "right" was governed by the Superannuation Act as amended from time to time. The content of that "right" depended on the will, from time to time, of the legislature that created the "right"[244]. The inherent variability of the "right" is reflected in the features of the statutory scheme itself. Any entitlements under s 18 are, and always have been, expressly "[s]ubject to this Act" and any entitlements are only "to benefits in accordance with" s 18[245]. Similarly, the underlying allowances are determined by the Remuneration Tribunal "from time to time as provided by this Part"[246].
[244]Chaffey (2007) 231 CLR 651 at 664 [25]. See also Quick and Garran, The Annotated Constitution of the Australian Commonwealth, 2nd ed (rev) (2015) at 573-574.
[245]s 18(1) of the Superannuation Act. See, eg, Chaffey (2007) 231 CLR 651 at 662 [18], 665 [30], 670-671 [49].
[246]s 7(1) of the RT Act.
The method for calculation of the retiring allowance, and each integer used by any method, was not fixed in permanent form at any particular date (whether at the date the plaintiffs entered Parliament, at the date they retired from Parliament or at a later date). Accordingly, even if the bundle of "rights" held by the plaintiffs (whether at the date they entered Parliament, at the date they retired from Parliament or at a later date) was property, as broadly construed[247], there was no property protected from acquisition by s 51(xxxi) and no acquisition of property within the meaning of s 51(xxxi)[248].
[247]See Chaffey (2007) 231 CLR 651 at 663-664 [21]-[25]; Telstra (2008) 234 CLR 210 at 230-231 [43]-[44]. See also Dalziel (1944) 68 CLR 261 at 284-285, 290, 295.
[248]Chaffey (2007) 231 CLR 651 at 665-666 [30]; WMC Resources (1998) 194 CLR 1 at 16-17 [15]-[16], 38 [86], 75 [203].
That view is reinforced by the history[249], purpose and object of the legislation that effected the alleged variation, modification or extinguishment. On the recommendation of the Belcher Review, the RT Impugned Provisions were introduced as preventative measures "so that any folding-in of allowances" for sitting parliamentarians did "not flow to the retirement benefits of members of [Parliament]"[250].
[249]See, eg, Chaffey (2007) 231 CLR 651 at 673 [60].
[250]See Australia, Senate, Remuneration and Other Legislation Amendment Bill 2011, Supplementary Explanatory Memorandum; see also Belcher Review at 13, 60-61, Recommendation 7.
The preventative measures were necessary because the Parliament adopted the Belcher Review's recommendation[251] that the entitlements framework for serving parliamentarians be simplified. In particular, the Belcher Review recommended that all salary matters for serving parliamentarians be determined independently by the Remuneration Tribunal following a work value assessment[252]. The Belcher Review considered that the level of parliamentary remuneration would be more transparent (as was desirable) if allowances providing a personal benefit, such as an electorate allowance and overseas study travel entitlements, were considered to be part of a serving parliamentarian's salary[253].
[251]See, eg, Belcher Review at 8.
[252]Belcher Review at 13, 58-60.
[253]Belcher Review at 59.
So, what mechanism did the preventative measures adopt? As seen earlier, and as recommended by the Belcher Review[254], the RT Impugned Provisions permitted the Remuneration Tribunal to provide that certain amounts not form part of the underlying reference used to determine the superannuation benefits of members of the scheme.
[254]Belcher Review at 61.
In that legislative context, the source of the power to enact the RT Impugned Provisions is the same as the RT Act. Parliament may legislate for the remuneration of members of the Senate and the House of Representatives. It is for the Parliament to decide the amount, nature and incidents of that remuneration. When Parliament decided in 2011 to adopt the recommendation of the Belcher Review that, to enhance transparency[255], the calculation of the salary of a parliamentarian would extend to include allowances which, up to that point in time, had not constituted the salary of a parliamentarian, it is not surprising that this required changes to be made to permit the excision of those allowances in the calculation of a retiring allowance. Why? The answer is that, because those allowances had not previously been available to a retired parliamentarian, there was no reason for the retiring allowance to be calculated by reference to them and increased accordingly. The RT Impugned Provisions simply prevented "any folding-in" of those allowances to the retiring benefits of members.
[255]Belcher Review at 59.
There is no suggestion here that Parliament legislated to modify or take away any accrued entitlements, or legislated to modify or take away accrued entitlements simply for the purpose of saving money, or because it was decided as a matter of policy that entitlements were too generous. Cases of that nature may or may not fall within s 51(xxxi)[256]. That is not this case.
[256]Theophanous (2006) 225 CLR 101 at 113-114 [7]. cf Peverill (1994) 179 CLR 226 at 237.
The RT Impugned Provisions and Determinations have nothing to do with the acquisition of property on just terms for a purpose in respect of which the Parliament has power to make laws. A law that qualifies retired parliamentarians' rights to the retiring allowance by permitting removal of allowances that would otherwise not be relevant to, and would improperly inflate, the retiring allowance is within the power to grant remuneration, a power given by s 51(xxxvi) read with s 48 or s 66 of the Constitution. It would weaken the effect of the principle of probity and good governance, which the RT Impugned Provisions were intended to provide, to place the laws within s 51(xxxi).
The RT Impugned Provisions and Determinations do not effect an "acquisition". The Commonwealth did not acquire anything or have any interest conferred on it by reason of any one of the RT Impugned Provisions and Determinations. The RT Impugned Provisions and Determinations cannot properly be characterised as a law with respect to the acquisition of property for a purpose for which the Parliament has power to make laws[257].
The third and fourth plaintiffs' challenge to the LGP Impugned Provisions
[257]Mutual Pools (1994) 179 CLR 155 at 188.
The "property" or "right"
The third and fourth plaintiffs, Mr Moore and Mr Cohen, submitted that they had a "right" to a LGP that entitled them to a certain number of free domestic return trips per year.
Prior to the enactment of the 2002 LGP Act, Mr Moore was entitled to 25 free domestic return trips per year with his LGP[258], while Mr Cohen was entitled to unlimited free domestic return trips per year with his LGP[259]. After the enactment of the 2002 LGP Act, Mr Moore and Mr Cohen were both entitled to 25 free domestic return trips per year with their LGPs pursuant to the table in s 11(2). The 2012 LGP Act reduced the entitlement to 10 free domestic return trips per year[260]. Certain provision was also made for spouses of LGP holders at each relevant time[261].
[258]Remuneration Tribunal, Determination 1993/18.
[259]Remuneration Tribunal, Determination 1976/6, as modified by Determinations 1977/9, 1980/8 and 1984/18.
[260]Item 6 of Sched 1 to the 2012 LGP Act.
[261]See, eg, Item 2 of the table in s 11(2) of the 2002 LGP Act.
Mr Moore and Mr Cohen challenged the validity of the LGP Impugned Provisions. They alleged that the LGP Impugned Provisions resulted in the acquisition of property within the meaning of s 51(xxxi) because they reduced the number of free domestic return trips to which holders of the LGP were entitled per year[262].
[262]Mr Moore claimed that the 2012 LGP Act resulted in an acquisition of his property otherwise than on just terms and Mr Cohen claimed that both the 2002 LGP Act and the 2012 LGP Act resulted in an acquisition of his property otherwise than on just terms.
Although it is convenient to refer to the subject matter as the "life gold pass" or "LGP", it is important not to allow those terms to obscure the fact that the "right" alleged to be the relevant item of property acquired otherwise than on just terms is a "right", the content of which has been often changed, to have certain travel fares paid by the Commonwealth. In particular, what forms of travel and what class of travel would be paid for, in what circumstances and how often, has often changed. Accordingly, when Mr Moore and Mr Cohen spoke of the LGP Impugned Provisions effecting an acquisition of their "right" to a LGP, the proposition had to be understood as being that an entitlement to have a certain number and kind of travel fares paid for by the Commonwealth had been acquired because the number of allowed fares had been reduced.
It is necessary to examine in more detail the position prior to, and then the nature and extent of the changes effected by, the LGP Impugned Provisions.
Position prior to the LGP Impugned Provisions
The LGP has had three phases in its life: as an administrative scheme from pre-Federation until 1976, as an allowance by determinations of the Remuneration Tribunal under the RT Act from 1976 to 2002 and then under its own legislative scheme – the 2002 LGP Act.
From pre-Federation (in respect of parliamentarians in the separate colonies) until 1976, the scheme was administrative and depended upon the exercise of executive power. The validity of that scheme is not in issue but is at least open to doubt[263]. The scheme for the issue of a LGP to certain serving (and, later, retired) parliamentarians has its origins in executive arrangements between the Commonwealth and State governments. Those arrangements involved the issue from time to time of passes, in the form of a gold plated medallion, to various persons, and the associated provision of travel privileges to those persons. The persons to whom such passes were issued, and the associated travel entitlements of persons who held such passes, developed over time and reflected the views current at various points in time.
[263]See Brown v West (1990) 169 CLR 195 at 202; [1990] HCA 7.
These passes were first issued to retired Commonwealth parliamentarians in 1923, in the form of a gold medallion, called a Gold Life Pass by the issuing authority. From 1955, the term "Life Gold Pass" was frequently used to describe the pass. These passes were also described officially from time to time by other descriptions including "life railway passes", "life passes", "all lines life passes" and "gold life rail passes".
From 1976 to 1994, the scheme was the subject of determinations of the Remuneration Tribunal under the RT Act. By a notice in writing dated 4 March 1976, pursuant to s 7(4)(b) of the RT Act, the Minister for Administrative Services requested the Remuneration Tribunal to enquire into and determine certain matters, including "Life Gold Pass". By its Determination 1976/6, the Remuneration Tribunal determined the criteria applicable to the issue and use of a LGP[264]. By the same Determination, the Remuneration Tribunal suspended the travel privileges associated with the LGPs held by sitting members of Parliament[265]. That Determination was not disapproved by either House of Parliament.
[264]See cll 2.28-2.33 of Determination 1976/6.
[265]cl 2.34 of Determination 1976/6.
From the coming into effect of Determination 1976/6 until 1 January 1994, the Remuneration Tribunal issued Determinations that modified the operation of the LGP scheme from time to time[266]. The effect of those Determinations made by the Remuneration Tribunal was to permit the holders of a LGP to travel at official expense for non-commercial purposes within Australia on scheduled commercial/commuter air services, mainline rail services and other government services, or by motor coach or other vehicles operating as regular carriers.
[266]See Determinations 1977/9, 1980/8, 1981/13 and 1984/18.

In 1993, the Remuneration Tribunal reviewed the LGP and imposed a cap of 25 free domestic return trips per year on members (who had not been Prime Minister) to whom a LGP was issued on or after 1 January 1994[267].
[267]Remuneration Tribunal, 1993 Review, (1993) at xxv and Determination 1993/18.
Changes effected by the LGP Impugned Provisions
With relevant effect from the commencement of Pt 3 of the 2002 LGP Act on 30 December 2002, Item 1 of the table in s 11(2) of the 2002 LGP Act provided that a former parliamentarian, other than a former Prime Minister, who held a LGP was entitled to a maximum of 25 free domestic return trips per year. Mr Cohen claimed that the 2002 LGP Act resulted in an acquisition of his property otherwise than on just terms. The 2002 LGP Act did not affect Mr Moore.
Section 30(2) of the 2002 LGP Act provided that a determination of the Remuneration Tribunal was to make provision for the circumstances in which a member will, on retirement from Parliament, qualify for a LGP. The determination may provide for different circumstances for different kinds of members[268]. However, s 30(1) of the 2002 LGP Act provided that a determination of the Remuneration Tribunal had no effect to the extent to which it was inconsistent with the 2002 LGP Act. That provision is important. It will be necessary to return to consider it.
[268]s 30(3) of the 2002 LGP Act.
The 2012 LGP Act then amended Item 1 of the table in s 11(2) of the 2002 LGP Act to provide that a former member who held a LGP, other than a former Prime Minister, was entitled to a maximum of 10 free domestic return trips per year[269]. Both Mr Moore and Mr Cohen claimed that the 2012 LGP Act resulted in an acquisition of their property otherwise than on just terms.
[269]Item 6 of Sched 1 to the 2012 LGP Act.
It was not in issue in this matter that the 2002 LGP Act and the 2012 LGP Act, insofar as they addressed the LGP, were enacted by Parliament under s 48 read with s 51(xxxvi) of the Constitution[270]. It is therefore not necessary to examine whether the LGP is an allowance of the kind referred to in s 48 of the Constitution.
[270]See Theophanous (2006) 225 CLR 101 at 113 [7], 121 [37].
The LGP Impugned Provisions invalid by reason of s 51(xxxi)?
The statutory provisions for a LGP, together with their administrative and recent legislative history, reveal that the "right" to a LGP suffers from a "congenital infirmity"[271]. Not only was the administrative origin of the LGP inherently unstable[272], but its continued existence, scope and incidents were, and remain, unstable.
[271]See WMC Resources (1998) 194 CLR 1 at 75 [203] citing Norman v Baltimore & Ohio Railroad Co 294 US 240 at 308 (1935).
[272]cf Brown v West (1990) 169 CLR 195 at 202.
The fragility and inherent variability of the prospective "right" to a LGP for serving members is made evident by s 7(1) of the RT Act providing that the Remuneration Tribunal shall "from time to time … determine, the allowances … to be paid … to members of the Parliament" (emphasis added). The statutory right that serving members had to the benefits provided by the LGP could be and was varied from time to time. At its highest, the prospective "right" to a LGP for serving members was subject to what Parliament "otherwise provided" and what the Remuneration Tribunal determined from time to time[273].
[273]See also Peverill (1994) 179 CLR 226 at 237; Georgiadis (1994) 179 CLR 297 at 305-306; WMC Resources (1998) 194 CLR 1 at 75 [203]; Chaffey (2007) 231 CLR 651 at 665-666 [30].
For example, as noted above, in 1993, the Remuneration Tribunal did limit the amount of trips per year for prospective LGP holders. A relevant Remuneration Tribunal determination also may provide for the circumstances in which a member will, on retirement from Parliament, qualify for a LGP. As seen earlier, the determination may provide for different circumstances for different kinds of members[274]. And the Remuneration Tribunal did make changes. It had previously amended the class of travel available to existing LGP holders[275]. That power of amendment was specifically retained by s 26 of the 2002 LGP Act.
[274]s 30(2) and (3) of the 2002 LGP Act.
[275]See cll 6.3-6.4 of Determination 1977/9, superseding cll 2.31‑2.32 of Determination 1976/6.
Mr Cohen and Mr Moore are not serving members but retired parliamentarians. The "right" which they had to a LGP, at retirement, still depended upon the statutory scheme, if any, as it stood from time to time. The "right" that a retired parliamentarian had to a LGP was and remains as fragile and inherently variable as the right of a serving parliamentarian. The content of the "right", at least from 1976, depended on the will, from time to time, of the legislature that created the "right"[276]. Not only its origin, but its continued existence, was and remains unstable.
[276]Chaffey (2007) 231 CLR 651 at 664 [25]. See also Quick and Garran, The Annotated Constitution of the Australian Commonwealth, 2nd ed (rev) (2015) at 573-574.
The 2002 LGP Act, and then the 2012 LGP Act, provided a new statutory scheme for the LGP for retired parliamentarians. That new statutory scheme arose because the Remuneration Tribunal expressed the view that it was the responsibility of the Government to address the "right" to a LGP for retired parliamentarians[277]. The Government did address that issue by introducing the 2002 LGP Act, and then the 2012 LGP Act, both of which Parliament enacted.
[277]Remuneration Tribunal, 1993 Review, (1993) at xxv.
Not only did each of the 2002 LGP Act and the 2012 LGP Act vary the "right" to a LGP for retired parliamentarians but s 30(1) of the 2002 LGP Act at all times expressly provided that a determination of the Remuneration Tribunal had no effect to the extent it was inconsistent with the 2002 LGP Act. The 2002 LGP Act, and then the 2012 LGP Act, made existing determinations of the Remuneration Tribunal under s 7(1) of the RT Act dealing with the "right" to a LGP for retired parliamentarians unenforceable to the extent that they were inconsistent with the 2002 LGP Act. That is not surprising. As seen earlier, the prospective "right" to a LGP for serving members was fragile and inherently variable, as was the "right" that a retired parliamentarian had to a LGP. To describe determinations made by the Remuneration Tribunal under s 7(1) of the RT Act in relation to a LGP as creating accrued statutory rights is inconsistent with the express words of the RT Act, the subsequent enactment and express terms of the 2002 LGP Act and the 2012 LGP Act, and the history of the various iterations of the LGP scheme. Those matters reveal that the "right" to a LGP suffers from a "congenital infirmity"[278]. Nothing in the Acts Interpretation Act 1901 (Cth) (whether s 8(c), s 8B or s 46(1)(a)[279] or any other provision) denied those results.
[278]See WMC Resources (1998) 194 CLR 1 at 75 [203] citing Norman v Baltimore & Ohio Railroad Co 294 US 240 at 308 (1935).
[279]As those provisions stood before the amendments made by the Acts Interpretation Amendment Act 2011 (Cth).
There could be no acquisition because the "right" was variable and could be and was amended from time to time. The "right" to the LGP held by Mr Moore and Mr Cohen was not property protected from acquisition by s 51(xxxi) and there was no acquisition of property within the meaning of s 51(xxxi)[280].
[280]WMC Resources (1998) 194 CLR 1 at 16-17 [15]-[16], 38 [86], 75 [203]; Chaffey (2007) 231 CLR 651 at 665-666 [30].
Conclusions and orders
For these reasons, the questions of law which the parties agreed in stating in the form of a special case for the opinion of the Full Court under r 27.08.1 of the High Court Rules should be answered as follows:
Question One: Do any, and if so which, of the following laws and Determinations of the Remuneration Tribunal constitute or authorise an acquisition of any, and if so what, property of the plaintiffs, or any of them, otherwise than on just terms, within the meaning of s 51(xxxi) of the Constitution:
(a)Remuneration Tribunal Act 1973 (Cth), ss 7(1A), 7(1B), 7(1C) and 7(2A);
(b)Remuneration and Other Legislation Amendment Act 2011 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 16A, 17A, 19, 20, 21(2));
(c)Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 2, items 1, 2, 3, 5, 6, 7, 8 and 9);
(d)Members of Parliament (Life Gold Pass) Act 2002 (Cth), s 11(2) (as originally enacted);
(e)Members of Parliament (Life Gold Pass) and Other Legislation Amendment Act 2012 (Cth), s 3 (insofar as it made the amendments or repeals provided for in Sched 1, item 6);
(f)Determination 2012/02, Pt 2 (cl 2.2);
(g)Determination 2012/03, Pt 2 (cl 2.3), Pt 3 (cl 3.1);
(h)Determination 2012/15, Pt 1 (cl 1.3 and cl 1.4 (insofar as it relates to cl 1.3));
(i)Determination 2013/13, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
(j)Determination 2014/10, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1);
(k)Determination 2015/06, Pt 2 (cl 2.2), Pt 3 (cl 3.3), Pt 4 (cl 4.1)?
Answer:  No.
Question Two:          If the answer to Question One is yes, to what, if any relief are the plaintiffs, or any of them, entitled in the proceedings?
Answer:  Unnecessary to answer.
Question Three:        Who should pay the costs of the proceedings?
Answer:  The plaintiffs.