Boggards, L. v McMahon, B.J

Re: LEENDERT BOGAARDS
And: MR. B.J. MCMAHON SITTING AS SENIOR MEMBER OF THE ADMINISTRATIVE APPEALS
TRIBUNAL and THE COMMONWEALTH OF AUSTRALIA
No. NSW G691 of 1987
Estoppel - Quasi-Judicial Tribunals - Prerogative Writs - Workers'
Compensation

COURT

IN THE FEDERAL COURT OF AUSTRALIA

NEW SOUTH WALES DISTRICT REGISTRY
GENERAL DIVISION
Pincus J.(1)

CATCHWORDS

ESTOPPEL - res judicata - issue estoppel - administrative tribunal decision.

QUASI-JUDICIAL TRIBUNALS - Administrative Appeals Tribunal - estoppel arising from its decisions - binding quality of its decisions.

PREROGATIVE WRITS - allegation that administrative tribunal functus officio - whether prohibition available - whether declaration in lieu or in addition.

WORKERS' COMPENSATION - Commonwealth Government employee - relation between determinations of delegate and A.A.T. decisions.

Administrative Decisions (Judicial Review) Act 1977, ss.5 & 6

Administrative Appeals Tribunal Act 1975, ss.43, 44 & 45

Judiciary Act 1903, s.39B

Compensation (Commonwealth Government Employees) Act 1971, ss.20, 24, 25 & 46(2)

Federal Court of Australia Act 1976, s.32

HEARING

BRISBANE

#DATE 20:5:1988

Counsel for the applicant: Mr P.J. Deakin

Solicitors for the applicant: Sparke, Helmore & Withycombe

Counsel for the second respondent: Mr A.R. Emmett Q.C. with Mr R.D. Cogswell

Solicitors for the second respondent: Australian Government Solicitor

ORDER

A writ of prohibition issue directed to Brian John McMahon sitting as a senior member of the Administrative Appeals Tribunal, prohibiting him from further proceeding in reference N87/899;

The respondent, the Commonwealth of Australia, pay the applicant's costs of and incidental to the proceedings to be taxed.

NOTE: Settlement and entry of orders is dealt with in Order 36 of the Federal Court Rules.

JUDGE1

The applicant seeks relief relating to a point which has arisen before the Administrative Appeals Tribunal ("A.A.T."); he claims review of a Tribunal decision under the Administrative Decisions (Judicial Review) Act 1977, relief under s.39B of the Judiciary Act 1903 or an appropriate declaration. The Senior Member filed a submitting appearance; the second respondent will be referred to as "the respondent".

The point the applicant desires to have determined by one or other of these means is whether the Tribunal is right in thinking that it is entitled to reconsider the correctness of a consent order it made on 21 April 1986 and which was varied on 14 May 1987. Before the Tribunal, the applicant argued that it had no right to do that, and that contention was rejected, the Tribunal holding that it would hear an application to review a determination made on the basis of the orders of the Tribunal I have mentioned. The determination related to the applicant's entitlements under the Compensation (Commonwealth Government Employees) Act 1971.
Since the dispute before me relates to the jurisdiction of the Tribunal and does not have to do with the substantive question sought to be raised before the Tribunal, it is necessary to explain the latter only in outline. Under the Act just mentioned (the Compensation Act) elaborate provision is made in s.25 for the mode of calculation of "average weekly earnings" of an injured employee. Once those earnings are assessed, the result is used in a calculation prescribed by s.46(2), which entitles a partially incapacitated employee to be paid weekly compensation equal to the lesser of two amounts. The first is a fixed sum which has been changed by statute from time to time, and the second is:

"the amount (if any) by which the average weekly earnings of the employee before the injury exceeds from time to time the amount per week that he is able to earn in some suitable employment or business ..."

There is an alternative possibility in s.46(2)(b), but it is unnecessary to deal with that here. The scheme, so far as relevant to this case, is that the injured employee gets the difference between his average weekly earnings before the injury and what he is able to earn. Section 25 provides, inter alia, for increase of the "average weekly earnings" if the pay the employee would have received if he had continued in his employment would have gone up "by reason of ... the completion by the employee of a particular period of service ..." - see s.25(9)(b). When he was injured, the applicant's position was that of "cadet aircrew", a rank which no longer exists. Apart from that difficulty, the problem in applying the provisions to the applicant has apparently been that his attaining a higher rate of pay, had he continued in his former employment, would have depended to some extent on factors other than completion of periods of service.
To put it shortly, the underlying dispute is whether compensation is payable on the assumption that the applicant would have received what might be described as the ordinary promotions.
The respondent's present stance appears to be that compensation should be assessed on the basis that the applicant would, during the whole of the relevant period, have remained a cadet - an impossibility. Assessing the compensation in accordance with the applicant's view involves, according to the respondent's contentions contained in the papers before me, some uncertainties, in particular as to the precise date on which the postulated promotions would have occurred. Nevertheless, it is convenient to call orders or determinations made on the basis that the applicant is entitled to the benefit of postulated promotions, "the applicant's approach".
The applicant enlisted in the RAAF in 1976 and was injured a few months later. He underwent surgical treatment and was then discharged on medical grounds. It is said that he remains partially incapacitated. On 11 August 1978 a delegate of the Commissioner for Employees' Compensation determined that the "Department of Defence is liable to pay compensation in respect of the said personal injury". A further determination was made on 19 June 1980, setting out the amounts to which the applicant was entitled from 31 March 1980 "to 4 May 1980 and from 6 May 1980 to a date to be determined by the Commissioner or his Delegate". Next, on 31 March 1981, a determination was made fixing the rates of compensation payable to 14 January 1981, and from 15 January 1981 until a date to be determined. The second determination of amounts payable conflicted with and expressly revoked the first; it set lower rates of compensation.
The applicant applied to the Administrative Appeals Tribunal for review of the determination of 31 March 1981, and on 15 April 1982, a member of the Tribunal gave a decision recording that the parties had reached agreement as to the terms of the decision. The Tribunal set aside the determination of 31 March 1981 and ordered the making of a new determination and that -

"the appropriate rate of compensation to be paid be assessed in accordance with Average Weekly Earnings and Ability to Earn as set out in figures shown in Schedule 'A' attached hereto, to which, it is noted, the parties agree."

The schedule set out in two columns the average weekly earnings and ability to earn for periods commencing on 22 December 1979 and ending on 14 February 1982 and for a period described as "15.2.82 and continuing". On 9 September 1982, a delegate of the Commissioner made a determination of compensation payable covering the period dealt with in the Tribunal's decision and then going further to 30 April 1982. The determination was made on the basis of the Tribunal's decision, that is, in accordance with the applicant's approach.

A further determination was made on 31 August 1984 setting out the amounts payable until 18 April 1984 and a determination of 3 June 1985, setting out the entitlement to 17 April 1985, followed. The latter was accompanied by a letter saying, in effect, that the applicant's approach was wrong, except to the extent that he was entitled to be treated as if he would have obtained the rank of pilot officer on completion of his training as a cadet; the letter explained that in the writer's view he was not entitled to be treated as having been promoted beyond that point.
The two determinations I have just mentioned were the subject of a further application for review by the present applicant. On 21 April 1986, the Tribunal made a consent order setting aside those determinations and directing the making of a new determination. The second paragraph of the order read as follows:

"That the appropriate rate of compensation to be paid be assessed in accordance with Average Weekly Earnings which are to be assessed upon the basis that two years after becoming a Pilot Officer the Applicant would have automatically progressed to Flying Officer and that after a further two years six months the Applicant would have progressed to Flight Lieutenant."

Mr Emmett Q.C., senior counsel for the respondent, argued that there was nothing in the order prescribing the way in which the entitlement to compensation should be calculated. He said that the order did not include a direction as to that point, but simply a direction that if it were thought relevant to have regard to future promotions, the facts set out in the passage I have quoted could be assumed.
That appears not to be a fair reading of par.2 of the order. It does not say that the appropriate rate of compensation to be paid is to be assessed, if the delegate thinks fit, in accordance with the method there mentioned.
The expression "average weekly earnings" in the order is obviously used in the same sense as it has in the Compensation Act; the intention of the order, expressed in the language used with sufficient clarity, was to settle the point that "average weekly earnings" within the meaning of the provisions discussed above were to be assessed on the basis mentioned.
By a letter of 25 September 1986 a writer described as "Director Appeals" contended that the order of the Tribunal of 21 April 1986 was incapable of rational implementation. The matter was referred to the Tribunal again, which conducted a hearing at which both parties were represented. The Tribunal directed by consent:

"That the document headed SCHEDULE containing columns of figures representing the earnings of Pilot Officers, Flying Officers, and Flight Lieutenants at appropriate periods are those earnings referred to in paragraph 2 of the order dated 21 April 1986 ..."

The schedule took the figures up to the date of the direction, 14 May 1987 and treated the applicant as having been promoted as contemplated by the earlier order. Reading the direction of 14 May 1987 with that of 21 April 1986, to which it referred, it became clear enough that the Tribunal had directed the payment of compensation in accordance with the rules set out in the former determination and the figures set out in the latter - the applicant's approach again.
It should be added that there is a slight inconsistency between the order made by the Tribunal in 1982, on the one hand, and the orders made in 1986 and 1987 on the other. The first order gave figures for the last period covered by it different from those resulting from the later orders. However, the amount involved in the difference is small, and no point was taken about that by either side, so I propose to disregard it.
On 17 June 1987 the delegate made a determination of entitlement to compensation in accordance with the Tribunal's orders of 21 April 1986 and 14 May 1987 and, therefore, in accordance with the applicant's approach. The respondent applied to review that decision of the Tribunal, on 4 November 1987.
The application was based on the ground that:

"The Commissioner for Employees Compensation erred in calculating the average weekly earnings in accordance with section 25 of the Act of Leendert Bogaards from 15.2.82 to a date to be determined. In that he erred in relying on the rates of pay applicable to a Pilot Officer, then Flying Officer, then Flt Lieutenant."

It will be noted that the date selected, 15 February 1982, is the beginning of the period covered by the Tribunal's orders of 1986 and 1987 and covered by the determination attacked. The relief sought is retrospective, covering nearly six years in which compensation has been paid under the applicant's approach.

The argument for the applicant was, in essence, that having previously decided the precise dispute sought to be brought before it, the Tribunal was functus officio and could not decide the whole matter again.
The Tribunal decided on 4 November 1987 that it had jurisdiction "to hear proceedings No. N87/899", the number given to the latest application to it. Amongst the reasons given for the Tribunal's view was (par. 14) that the orders previously made were consent orders and therefore "the legality of the proposed method of calculation of average weekly earnings has not been tested". Counsel for the respondent did not seek to support that reason, conceding that both the doctrine of cause of action estoppel and that of issue estoppel apply to the Tribunal and that those doctrines apply to orders made by consent. The correctness of these concessions is discussed below.
A further reason given by the Tribunal was (par.17) that if the consent orders were ultra vires then they could be set aside by the Tribunal. Assuming that to be so, still it is clear that there is no question of the orders being ultra vires. There is admitted to be room for argument as to the proper mode of calculation of the compensation payable. If the mode agreed to was not that at which the Tribunal would have arrived after a contested hearing, that does not make its consent order ultra vires, nor did the respondent so contend.
Lastly, after dealing with the lateness of the present respondent's application to it (a question no longer in issue), the Tribunal held that the application challenging the latest determination "is properly before the Tribunal for review" which, in the context, plainly meant that there was jurisdiction to hear it.
The respondent disputed this Court's jurisdiction to grant the applicant any relief, arguing that, whether or not the Tribunal was entitled to reconsider the correctness of the consent orders I have mentioned, there was no power to interfere until the completion of the hearing before the Tribunal.
Ordinarily, one would be inclined to say that, whether or not the Court has power to do so, it would be inconvenient to interfere before the conclusion of the Tribunal's proceedings. The history of this dispute is, however, such that there is much to be said for this Court's taking a step, if it is empowered to do so, to bring to a halt a series of disputes involving substantially the same point.
On three occasions, the Tribunal has been invited to make consent orders giving effect to a view of the law favourable to the present applicant; the Tribunal has done so and those orders have been acted upon. The Tribunal has now been invited to consider the point afresh, with a view to producing the result that two of its three previous orders and what was done under them over a period of years would be invalidated. No rational explanation has been advanced by the respondent for its change of heart; it apparently now repents of having thrice consented, with every appearance of deliberation, the very considerations on which it now relies having been distinctly raised.
If the three orders in question had no binding effect between the parties, nor presumably would thirty-three such orders. The important question is whether consent orders of the Tribunal, being on their face determinative of the rights of the applicant under the Compensation Act, had in truth only an interim or provisional effect.
It was pointed out on behalf of the respondent that under the Compensation Act there is a Commissioner who may delegate his functions under s.24, and who is empowered to make determinations under s.20. They are not final, however, as they may be reconsidered by the Commissioner and varied or revoked under s.20(4). The question whether, in the absence of express words, such a variation or revocation could have retrospective effect - destroying accrued rights - was not debated before me. It was, however, contended, as I understood the argument, that the power in the Commissioner to revoke or vary determinations at will overrode the authority of the A.A.T., permitting the Commissioner or his delegate, by use of the power in s.20(4), to depart from directions given by the A.A.T.
It appears to me that the better view is that the A.A.T. (applications to which are governed by Part V of the Compensation Act) has power to make decisions by way of review of what the Commissioner has done, which bind the Commissioner as well as the parties: see Re Devine and Commonwealth of Australia (A.A.T., Davies J. presiding) 5 ALN N28 at p.N30.
The view just mentioned is that taken by the Commissioner, who regarded himself as bound to act in accordance with the directions of the Tribunal contained in its two more recent orders, in making his determination.
It was argued on behalf of the applicant that there is power in this Court to review decisions of the A.A.T. under the Administrative Decisions (Judicial Review) Act. The respondent argued that, although there is nothing in the Administrative Decisions (Judicial Review) Act to exclude the A.A.T. from the scope of review under ss.5 & 6, when one considers the scheme of that Act and the Administrative Appeals Tribunal Act 1975 (A.A.T. Act) it becomes clear that this Court's jurisdiction to review what is done in the A.A.T. is confined to the methods set out in ss.44 and 45 of the A.A.T. Act. I have found it unnecessary to resolve that question.
Next, it was argued that prohibition could not be granted under s.39B of the Judiciary Act because the error, if there was one, was not jurisdictional; reference was made for the applicant to such authorities as The Queen v. Gray; Ex parte Marsh (1985) 157 CLR 351. It is my view that, if the Tribunal is not entitled to deal with the application before it, that is for a jurisdictional reason, namely that the precise issue sought to be brought before the Tribunal has been expressly determined by its previous orders, and that the Tribunal is functus officio as to the necessary legal effect of its orders and has no power to review them. A similar objection was treated by the House of Lords as a jurisdictional one in Spackman's case (below).
Further, it is my opinion that this Court has jurisdiction to make a declaration on the point whether the A.A.T. is functus officio.
The claim for a declaration is sufficiently connected with the other claims to be an associated matter within the meaning of s.32 of the Federal Court of Australia Act 1976. Therefore, whether or not the applicant is entitled to succeed under the Administrative Decisions (Judicial Review) Act or under s.39B of the Judiciary Act, the Court may grant a declaration. Examples of declarations having been made in analogous circumstances include Forster v. Jododex Australia Pty Limited (1972) 127 CLR 421. There, a special tribunal was appointed by statute to deal with matters arising under its provisions (see p.427), but before the conclusion of the proceedings before it, the Supreme Court of New South Wales granted a declaration determinative of the parties' rights. A majority of the High Court (Walsh J. doubting) held that there was power to grant a declaration and that the discretion to do so had not been improperly exercised. The leading judgment on that point, that of Gibbs J., accepted the correctness of Lord Radcliffe's statement that:

"After all, it is doubtful if there is more of principle involved than the undoubted truth that the power to grant a declaration should be exercised with a proper sense of responsibility and a full realisation that judicial pronouncements ought not to be issued unless there are circumstances that call for their making. Beyond that there is no legal restriction on the award of a declaration" (p.438).

A similar result - i.e. the grant of a declaration during the currency of proceedings before another tribunal - ensued in Sankey v. Whitlam (1978) 142 CLR 1.

The more difficult point is whether it would be right to grant the applicant relief now. What has happened is that an important point as to the powers of the Tribunal has arisen at an interlocutory stage. The Full Court has held that there is no right of appeal to this Court in such circumstances: Director-General of Social Services v. Chaney (1980) 31 ALR. 571. Nevertheless, from time to time it must be convenient to have such a question decided by this Court before the whole dispute is finally concluded before the Tribunal. That is likely to be so where a considerable saving of time and cost may be effected by avoiding the necessity of a long and complex hearing on disputed facts before the Tribunal.
This is plainly not such a case. It might well have been more convenient to have concluded the hearing before the Tribunal rather than interrupt it by the proceedings which have come before me, but since the case has come here and has been fully argued, it should be considered. In coming to that view, I have been influenced, in particular, by two circumstances. One is that, as far as the authorities I have examined show, the important question of estoppel arising out of decisions of the Tribunal has never arisen as a central point in any case in this Court. Secondly, I am influenced by the unfortunate history of the litigation; the respondent has more than once changed its stance by consenting to orders in conformity with the applicant's view of the law and then declining to accept the resultant orders. The procedural objection made here by its counsel should not evoke a warm response from the Court.

Estoppel
The Administrative Appeals Tribunal, whether or not constituted by a judge, is one of a class which does not in general exercise judicial power: Drake v. Minister for Immigration and Ethnic Affairs (1979) 24 ALR 577 at p584. Such bodies, however, may have the function of ascertaining facts and applying the law to them: The Queen v. Trade Practices Tribunal Ex parte: Tasmanian Breweries Proprietary Limited (1970) 123 CLR 361 at p411. That decisions of the Tribunal may be based on, or indeed consist of, determinations of questions of law is necessarily implicit in s.44(1), which gives the right of appeal to this Court on such questions, and s.43(2B) recognizes its right to resolve questions of fact.
The Tribunal may, if an application before it succeeds, make an order which is then deemed to be a decision of the original decision-maker, under s.43(6). It may, in such a case as this, substitute its own decision for the determination of the delegate; but that substituted decision cannot be itself the subject of a further application to the Tribunal, as s.43(6) makes clear.
The other sort of decision the Tribunal can make is to remit the matter "for reconsideration in accordance with any directions or recommendations of the Tribunal" under par.(ii) of s.43(1)(c); then s.43(6) does not apply.
It is noticeable that the A.A.T. Act nowhere says expressly whether either sort of decision is binding. It is necessarily implicit in the provisions relating to the first class of decision just discussed - i.e. those where the Tribunal substitutes a new decision for that challenged - that the Tribunal's decision is at least as binding as that which was challenged. The binding quality of decisions of the other sort, where the matter is merely remitted for reconsideration, is not so obvious. Whatever may be the position as to "recommendations" of the Tribunal, in my opinion the word "directions" imports a binding quality. The intention is that the directions shall constrain the decision-maker in making his new decision, and that the new decision may not lawfully be made in a way which conflicts with the directions. In Arthur John Spackman v. The Plumstead District Board of Works (1885) 10 App.Cas.229 at p.235, Lord Selborne L.C., spoke of a statute providing for an administrative decision:

"... 'decided' implies that there is matter which may admit of difference, which may require determination. Prima facie that would mean determination so as to bind those who are to be affected by it."

It would seem easy enough to conclude that, to the extent that the Tribunal deals directly with a decision under review (for example by substituting another), its functions are exhausted. It would be absurd to suppose that the legislature intended that the Tribunal, having on Monday set aside a decision under review, should have jurisdiction on Tuesday (on precisely the same facts) to affirm it, perhaps acting by a different member. The same result must follow where the Tribunal's decision is made by consent; at least as a general rule, a consent order can support a plea of res judicata: In re South American and Mexican Company; Ex parte Bank of England (1895) 1 Ch 37 at pp45 and 50; Kinch v. Walcott (1929) AC 482 at p493; Isaacs v. The Ocean Accident and Guarantee Corporation Ltd (1958) 58 SR (NSW) 69 at p 75; The Administration of the Territory of Papua and New Guinea v. Daera Guba (1972-73) 130 CLR 353 at p 454.9; Chamberlain v. Deputy Commissioner of Taxation (ACT) (1987) 71 ALR 61 (reversed by the High Court, 19 May 1988 - unreported) and SCF Finance Co. Ltd v. Masri (No. 3) (1987) 1 All ER 194.
The current edition of Spencer Bower's "The Doctrine of Res Judicata" commences with the sentence: "A res judicata is a judicial decision, pronounced by a judicial tribunal". However, the author goes on to explain that the word "judicial" is, in this context, used as covering many tribunals, not being courts, set up under statute (par.24). The author had found extremely few cases in which an English civil authority had been held not to be a "judicial tribunal" (par.29), for this purpose. For example, arbitrators' awards create estoppels.
The important decision of the High Court in The Administration of the Territory of Papua and New Guinea v. Daera Guba (1972-73) 130 CLR 353, referred to above, concerned ownership of land which had previously been the subject of a decision of a body called the "Land Board". That was not a court, but was an ad hoc body set up under an ordinance to determine the ownership of eight specified parcels of land. Its conclusions were in the form of a series of answers to questions. It was not bound by "technical rules" (p.402). Barwick CJ held that its decision created an estoppel and McTiernan and Menzies JJ. agreed.
Gibbs J. held that the Board's decision created an
estoppel, which was not thought to be an issue estoppel, apparently because "the Board decided one of the very questions that falls for decision in the present case" (p.452). Gibbs J. rejected the contention that there could be no estoppel because a Land Board's decision was not a judicial one, drawing attention to the fact that a court martial's decision may estop although not made in the exercise of judicial power. His Honour, referring inter alia to the discussion in Spencer Bower (above) remarked:

"The doctrine of estoppel extends to the decision of any tribunal which has jurisdiction to decide finally a question arising between parties, even if it is not called a court, and its jurisdiction is derived from statute or from the submission of parties, and it only has temporary authority to decide a matter ad hoc ..."

Stephen J. agreed with the reasoning of Gibbs J. on the question of estoppel (p.460).
This decision makes it clear that statutory tribunals' decisions, although not made in the exercise of judicial power in the constitutional sense, may create estoppels. There being no feature of the Administrative Appeals Tribunal which appears to be adequate to distinguish it from the Land Board discussed in the Daera Guba case, I think the decision must be applied to the former body. It leaves open, however, the question whether an issue estoppel may arise from such a decision.
With the exception of Hoystead v. Commissioner of Taxation (1926) AC 155, a line of English cases culminating in the decision of the Privy Council in Caffoor v. Commissioner of Income Tax, Colombo (1961) AC 584, consistently rejects the application of issue estoppel to decisions of taxation and rating boards, deciding similar questions as to successive assessments. In the Caffoor case, Lord Radcliffe said that this view "may be ... somewhat anomalous ..." (p.599). Applied to the present case, these authorities would yield the result that the Tribunal would be free to determine that an applicant was entitled to compensation under the Act for a certain period and later decide (nothing having changed) that he was not entitled in respect of a later period, which would indeed seem anomalous.
Such a result does not appear so odd, however, if the first decision is made by consent; see the discussion by Mr Kelly in 84 LQR 362.
There are two decisions of the Full Court of this Court which should incline one against holding the doctine of issue estoppel to be applicable to proceedings in the A.A.T.; in neither was the Daera Guba case considered. The first is Minister for Immigration and Ethnic Affairs v. Daniele (1981) 39 ALR 649, a deportation case. Daniele, who had been convicted of manslaughter since migrating here, had the evidence at his trial re-examined by the A.A.T. and complaint was made of that by the Minister on appeal. The Court held that the Tribunal was entitled to examine the evidence itself because "Issue estoppel ... can not have any place in proceedings of the Tribunal ..." (p.654). That view was referred to with approval by the Full Court in The Commonwealth of Australia v. Annunziata Sciacca (unreported, 31 March 1988), but the Court declined finally to decide the question, apparently regarding it as not having been concluded by Daniele.
I have come to the conclusion, however, that it is inappropriate to determine, in this case, the application of the doctrine of issue estoppel to decisions of the A.A.T. As I remarked during the course of argument, it might have been more convenient if this important question had been raised in the first instance before a Full Court. It is true that there is a likelihood, perhaps sufficient to ground a declaration, that in the immediate future will need to be a decision on the question whether the view of the law "assumed" (to use the terminology in Mr Kelly's article) by the consent orders of the A.A.T. can be departed from, as to this applicant's injury. But the only question immediately before the Court is whether the Tribunal has jurisdiction to review the determination of the Commissioner's delegate, made strictly in accordance with the orders of the Tribunal. The determination carries the applicant's right to compensation a few weeks beyond the dates mentioned in the last order of the Tribunal, but the determination is nevertheless one directly implementing the Tribunal's orders. The Tribunal cannot review the determination on the ground sought to be raised, whether or not inhibited by issue estoppel, because it has already dealt with that precise dispute.
I should add that the High Court's reasons in the Chamberlain case (above) do not appear to me to cast doubt on the propriety of treating this as a case depending on "cause of action estoppel". That is so, although here as in Daera Guba, the estoppel arises from a decision in which no cause of action in the ordinary sense was set up.
I have considered whether there should be a declaration as well as a writ of prohibition. Were the question of the nature of the error made a matter of real doubt, I would do so; but it seems clear enough that it is jurisdictional.
It will therefore be ordered that a writ of prohibition issue directed to Mr Brian John McMahon sitting as a senior member of the Administrative Appeals Tribunal, prohibiting him from further proceeding in reference N87/899. The respondent, the Commonwealth of Australia, must pay the costs of the proceedings here.

[1988] FCA 233

20 MAY 1988