The State of South Australia v Milisits - [2013] SASC 189

SUPREME COURT OF SOUTH AUSTRALIA
(Appeal from a Master: Civil)
THE STATE OF SOUTH AUSTRALIA v MILISITS
[2013] SASC 189
Judgment of The Honourable Justice Stanley
13 December 2013
DEFAMATION - ACTIONS FOR DEFAMATION
PROCEDURE - DISCOVERY AND INTERROGATORIES - DISCOVERY AND INSPECTION OF DOCUMENTS - DISCOVERY OF DOCUMENTS
PROCEDURE - DISCOVERY AND INTERROGATORIES - DISCOVERY AND INSPECTION OF DOCUMENTS - PRODUCTION AND INSPECTION - GROUNDS FOR RESISTING PRODUCTION - PUBLIC INTEREST IMMUNITY
The respondent has brought an action in defamation against the appellant in relation to three publications by the appellant which allegedly impute that the respondent was engaged in the production and sale of custard Berliner buns infected or contaminated with salmonella. The appellant denies these imputations but says, inter alia, that the publication was justified based on the results of survey interviews conducted by the Department of Health's Communicable Diseases Control Branch ("CDCB") with persons who had contracted salmonella. The appellant disclosed documents that recorded the results of these interviews. Those documents had redacted any information that would identify the interviewees. A Master granted an application by the respondent that the appellant produce unredacted copies of the documents.
Whether the redacted information is relevant. If relevant, whether the information is protected from disclosure because it attracts public interest immunity.
Held (allowing the appeal):
1. There is no proper basis for refusing disclosure of the redacted information on the ground of relevance (at [16]-[21]).
2. The Master failed to direct his attention to the threat posed to the ability of the CDCB to obtain cooperation in future from infected persons in the provision of vital information concerning the outbreak of communicable disease where they could not be assured that their identification and the information they provided would be kept confidential (at [32]).
3. The potential for harm to the public interest that would result from disclosure of information identifying the interviewees who provide information to the CDCB outweighs the public interest in the litigation of the respondent obtaining the information which would permit it to identify the interviewees for the purposes of testing their recorded responses to the surveys relied upon by the appellant in making the impugned publications (at [33]-[38]).
Food Act 2001 (SA) s 110; Public and Environmental Health Act 1987 (SA) s 42, s 42A; South Australian Public Health Act 2011 (SA) s 99, s 100; Census and Statistics Act 1905 (Cth), referred to.
Harris Scarfe v Ernst & Young (No 10) (2006) 204 FLR 165; Adelaide Brighton Cement Ltd v State of South Australia (1999) 75 SASR 209; Medical Board of South Australia v Fisher & Ors (2000) 76 SASR 242; The Australian Statistician v Leighton Contractors Pty Ltd (2008) 36 WAR 83; Kirby v Prisoners' Review Board (No 2) [2010] SASC 280; Alister v The Queen (1983-84) 154 CLR 404; R v Young [1999] NSWCCA 166; Rogers v Home Secretary [1973] AC 388; D v National Society for the Prevention of Cruelty to Children [1978] AC 171; Royal Women's Hospital v Medical Practitioners Board of Victoria [2006] VSCA 85; State of Victoria v Brazel (2008) 19 VR 553, considered.

THE STATE OF SOUTH AUSTRALIA v MILISITS
[2013] SASC 189
Appeal from a Master
STANLEY J:
Introduction

This is an appeal from a Master.
The respondent has brought an action in defamation against the appellant. The respondent is a well-known baker in South Australia. The action is brought in relation to publications by Dr Kevin Bucket, the Public Health Director of the Department of Health, during press conferences on 4 February 2011 and 18 February 2011, and a radio interview on 7 February 2011. The respondent complains of statements by Dr Bucket on these three occasions which the respondent alleges conveyed imputations that the respondent was engaged in the production and sale of custard Berliner buns infected or contaminated with salmonella.
The appellant denies that these imputations arise from the pleaded publications but says, in any event, that the publication was justified, was made on an occasion of qualified privilege, and was protected by a statutory immunity conferred pursuant to s 110 of the Food Act 2001 (SA) (“the Food Act”). By his reply the respondent alleges the appellant was actuated by malice in publishing the impugned statements.
It is common ground between the parties that no trace of salmonella was found in the respondent’s factory, nor in any custard Berliner bun produced by his business.
The appellant, by its defence, however, pleads that the publications complained of were justified on the basis that there was sufficient epidemiological evidence in the appellant’s possession which supported a conclusion that some of the respondent’s products were contaminated with salmonella. This evidence included the results of survey interviews conducted by the Department of Health’s Communicable Diseases Control Branch (“CDCB”) with persons who had contracted salmonella.
The appellant disclosed documents that recorded the results of these interviews. Those documents had redacted any information that would identify the interviewees.
The respondent filed an application seeking an order that the appellant produce unredacted copies of these documents. The Master ordered that:
The appellant produce unredacted copies of the appellant’s disclosure documents numbered 1.1.14, 1.1.68, 1.1.136, 1.1.137, 1.1.138 and 1.1.224; and
The respondent has liberty to apply for production from the appellant of unredacted copies of the appellant’s disclosure documents numbered 1.1.30, 1.1.82, 1.1.223, 1.1.240, 1.1.266, 1.1.267, 1.1.287 and 1.1.288.
The appellant appeals these orders.
Issues on appeal
The appeal raises two issues. First, is the redacted information relevant? Secondly, if relevant, is the information protected from disclosure because it attracts public interest immunity?
The Master’s reasons
The Master held that the information contained in the documents identifying the interviewees was relevant and did not attract public interest immunity. In relation to the issue of relevance, the Master said:
[T]here are two essential bases upon which the defendant opposes the provision of that information. Firstly, it argues that it is not directly relevant to any issue on the pleadings between the plaintiff and the defendant. The defendant asserted in argument that it would not rely at trial on anything other than the redacted documents, copies of which it had supplied to the plaintiff. It would not in any circumstances call any of the persons who provided the case questionnaires. As the defendant asserted that the statements made by Dr Buckett were justified by the epidemiological evidence, the actual identity of those persons who provided the base material for that evidence was irrelevant. However, the defendant goes further than that in its defence at paragraph 19, when it pleads as justification that “the matters complained of were true or substantially true in substance and in fact”. It relies on provisions in the Food Act in paragraph 25 of the defence, and in particular in sub-paragraph 25.3 it relies on the powers to make binding orders and to issue publication of warnings to the public “where there are reasonable grounds to believe than [sic] an order is necessary to prevent or reduce the possibility of a serious danger to public health …”. Further, it relies on the statutory immunity provided by s 110 of the Food Act, which provides protection for “an honest act or omission in the exercise or discharge, or purported exercise or discharge, of a power, function or duty under this Act”.
In relation to the issue of public interest immunity, the Master held that the test for whether the information in this case attracted public interest immunity required a balancing exercise between the public interest in the appellant maintaining the confidentiality of persons providing information to it concerning communicable diseases and the public interest in a court having all relevant evidence available to it in the adjudication of a legal dispute. He said:
In my view, the relevant aspects of the case questionnaires are limited to the informant’s eating pattern over a period of 7 days or so prior to becoming ill with Salmonella. The information contained therein when limited to that material is not particularly sensitive. It would be reasonable to suspect that many of those informants would not have any particular objection to that information and their contact details being made available to the plaintiff in the circumstances of this particular matter. In any event, in carrying out the necessary balancing exercise the requirement that evidence necessary for justice to be done should be freely available to those who litigate in our Courts (Stephen J in Sankey v Whitlam (supra) at 48-49) outweighs in this case any prejudice to the national or public interest in preventing that disclosure.
The pleadings
It is necessary to understand the way in which the parties have pleaded their case in order to resolve the issue of relevance.
The respondent pleads the following imputations:
25.1That the Plaintiff was engaged in the production and/or sale of product infected or contaminated with Salmonella and/or bacteria;
25.2That the Plaintiff was engaged in the production and/or sale of product that was a risk to human health;
25.3That the Plaintiff allowed his business to be conducted in a manner that resulted in its product becoming infected or contaminated with Salmonella and/or bacteria.
The appellant pleads its defence of justification as follows:
19.The defendant further says in answer to the whole Statement of Claim that insofar as it may be found that the matters complained of were published by the defendant and identified the plaintiff in his personal capacity (which is denied) and to be defamatory of him in their natural and ordinary meaning or as bearing any other meanings which are defamatory (which is denied), the matters complained of were true or substantially true in substance and in fact.
20.There was sufficient epidemiological evidence in the defendant’s possession which supported a conclusion that some of Vili’s Custard Berliners were contaminated with Salmonella. This evidence was:-
20.1 In the week leading up to 28 January 2011, twenty-three cases of Salmonella Typhimurian phage type 9 (STm9) had been reported;
20.2 The Communicable Disease Control Branch (CDCB) of the Department of Health commenced an investigation pursuant to its powers under the Public and Environmental Health Act 1987;
20.3 The investigation was conducted by CDCB staff interviewing those people who had been infected with STm9 and obtaining details about what they had eaten over the seven days before they became ill and where they purchased the food from;
20.4 By 28 January 2011 eight interviews had been conducted and two people had reported eating Vili’s Custard Berliners;
20.5 By 30 January 2011, fifteen people had been interviewed and four of these reported eating Vili’s Custard Berliners;
20.6 On 1 February 2011 CDCB received a further report of seven cases of individuals experiencing gastrointestinal illness after consuming Vili’s Custard Berliners at a staff workplace donut day. All the food for the day had come from Vili’s;
20.7 By 4 February 2011 fifty-eight people reported eating a custard Berliner in the week before they became ill. Of these fifty-eight people, twenty-eight people reported eating Vili’s Custard Berliners in the week before they became ill;
20.8 On 4 February 2011 a case-controlled analysis was conducted which found that an ill person was thirty-eight times more likely to have eaten a Custard Berliner compared to a healthy person;
20.9 By 17 March 2011, a total of forty-four people who had tested positive to STm9 had eaten Custard Berliners in the week before they became ill. Of these forty-four, nineteen reported eating Vili’s custard Berliners;
20.10 Approximately forty per cent of all persons infected with STm9 during this period required hospitalisation which was about double the rate since 2005.
Relevance
In Harris Scarfe v Ernst & Young (No. 10)[1] Debelle J held that it is a well-established and accepted practice that, where a discoverable document contains material which is both relevant and irrelevant, the document can be produced for inspection with the irrelevant parts of the documents masked. While as a general rule the whole of a discovered document is produced for inspection, where there are issues as to confidentiality, irrelevant parts of a document will usually be masked.[2]
[1] [2006] SASC 325, (2006) 204 FLR 165.
[2] [2006] SASC 325 at [22] – [24], (2006) 204 FLR 165 at 171 – 173.
The documents were disclosed by the appellant. There is no dispute that they are directly relevant on the pleading of justification. The issue is whether the information identifying the interviewees is relevant. I am satisfied the information which discloses the identity of the interviewees was obtained in circumstances that imposed upon the appellant an obligation to maintain confidentiality. First, because the appellant promised the interviewees that the information they provided would be kept confidential. Secondly, and more importantly, because the work of the CDCB is subject to statutory obligations of confidentiality. On the hearing of the appeal, there was a question as to whether the relevant statute is the Public and Environmental Health Act 1987 (SA) or the South Australian Public Health Act 2011 (SA). It is unnecessary to determine which Act applies because the statutory provisions which impose obligations of confidentiality on the persons undertaking the surveys are in pari materia.[3]Those provisions prohibit a person who obtains personal information about another person in the course of the performance of official duties from intentionally disclosing that information except to the extent authorised by the statute. Those exceptions include where disclosure is required by law or a court or a tribunal constituted by law. The information which is protected is medical information or information relating to a person’s personal affairs.
[3] Public and Environmental Health Act 1987 (SA) s 42 and s 42A; South Australian Public Health Act 2011 (SA) s 99 and s 100.
In my view, information identifying the names and addresses of the interviewees is confidential information for the purposes of the statutes. Accordingly, I am satisfied that it would be proper in accordance with the principle in Harris Scarfe to mask those parts of the documents which disclose that information if it is irrelevant.
The appellant submits that information disclosing the identities of the interviewees is irrelevant. While the respondent is entitled to test the epidemiological evidence relied upon by the appellant in making the impugned publications, it does not need to interview the survey respondents in order to do so. The appellant submits the respondent is engaged in a fishing expedition, hoping something will turn up if he speaks to the interviewees. Further, it submits there would be little utility in speaking with those who were interviewed by the CDCB for the purpose of testing the answers they gave at interview now because of problems related to the failings of memory given the effluxion of time and the risk of recall bias.
The respondent submits that the identities of the interviewees are relevant, or at least the disclosure of this information serves a legitimate forensic purpose because it is necessary for the respondent to be able to test the answers that were given by the interview subjects in order to determine whether their answers were accurately or completely recorded, or whether they may have been mistaken in some of the answers they gave. He submits that this would be directly relevant to the probative value of the data upon which the appellant seeks to rely for the purposes of mounting its defence of justification of the imputation that the respondent produced and/or sold Berliner buns infected or contaminated with salmonella. On that basis the respondent is entitled to speak to the interviewees for the purposes of the preparation of his case for trial. He submits that logic suggests that far from being irrelevant, evidence from the interviewees is likely to be probative of the reliability of the survey. Insofar as the appellant contends that there is no utility in testing the answers given by the interviewees now because of the problems of faulty memory or recall bias, these are matters which only go to weight rather than relevance.
In my view, the respondent’s submission must be accepted.
The appellant is seeking to justify the publication by it that the respondent produced and/or sold Berliner buns infected or contaminated with salmonella. It seeks to justify this imputation, at least in part, by reliance upon information obtained from the survey interviews. There is an obvious forensic purpose in the respondent being able to test the information obtained through the surveys. This is not a fishing expedition. A fishing expedition involves seeking disclosure of documents in the hope that something will turn up of assistance to the party seeking disclosure in the documents themselves. In this case, the contents of the documents have been disclosed except for any information which identifies the interviewees. The information in the disclosed documents revealing the identities of the interviewees potentially is relevant to any proper testing of the epidemiological evidence. Whether any basis exists to impugn the answers given by the respondents in their interviews is purely speculative at this stage. But that does not make their identities irrelevant. The criticism of the methodological flaws that might be inherent in the process of testing the interviewees’ answers merely goes to the weight of such evidence, not its relevance. In my view, the redacted information is relevant. Accordingly, there is no proper basis for refusing disclosure of the redacted information on the ground of relevance. That leaves the issue of whether the information is protected from disclosure by public interest immunity.
Public interest immunity
The principles applicable to a claim of public interest immunity are helpfully summarised by Debelle J in Adelaide Brighton Cement Ltd v State of South Australia[4] and were cited with approval by the Full Court in Medical Board of South Australia v Fisher & Ors[5] as follows:
[4] [1999] SASC 379, (1999) 75 SASR 209.
[5] [2000] SASC 92 at [37], (2000) 76 SASR 242 at 248.
(1)The general rule is that a court will not order the production of a document, although relevant and otherwise admissible, if it would be injurious to the public interest to disclose it: Sankey v Whitlam (1978) 142 CLR 1 at 38.
(2)However, the court recognises that there are two aspects to the public interest which may conflict. They were described by Lord Reid in Conway v Rimmer [1968] AC 910 at 940 in these terms:
There is the public interest that harm shall not be done to the nation or the public service by disclosure of certain documents, and there is the public interest that the administration of justice shall not be frustrated by the withholding of documents which must be produced if justice is to be done.
Those observations were adopted by Gibbs ACJ in Sankey v Whitlam at 38. Stephen J expressed the competition between these two aspects of the public interest in these terms in Sankey v Whitlam at 48-49:
These principles, stated in their broadest form, each reflect different aspects of the public weal. Because disclosure to the world at large of some information concerning sensitive areas of government and administration may prejudice the national interest there exists a public interest in preventing the curial process from being made the means of any such disclosure. At the me time the proper administration of justice, of prime importance in the national interest, requires that evidence necessary if justice is to be done should be freely available to those who litigate in our courts.
(3)It is the duty of the court, not the privilege of the executive, to determine whether a document will be produced or may be withheld: Sankey v Whitlam at 38, 58-59, 95-96. As Stephen J said in Sankey v Whitlam at 58, a claim to Crown privilege has no automatic operation; it always remains a function of the court to determine that claim.
(4)The court determines whether a document should be produced or withheld by deciding whether the public interest which requires that the document should not be produced outweighs the public interest that a court in performing its functions should not be denied access to relevant evidence: Sankey v Whitlam at 38-39. In Commonwealth v Northern Land Council at 616 the court approved the following observations of Gibbs ACJ in Sankey v Whitlam at 43.
I consider that although there is a class of documents whose members are entitled to protection from disclosure irrespective of their contents, the protection is not absolute, and it does not endure for ever. The fundamental and governing principle is that documents in the class may be withheld from production only when this is necessary in the public interest. In a particular case the court must balance the general desirability that documents of that kind should not be disclosed against the need to produce them in the interest of justice. The court will of course examine the question with especial care, giving full weight to the reasons for preserving the secrecy of documents of this class, but it will not treat all such documents as entitled to the same measure of protection - the extent of protection required will depend to some extent on the general subject matter with which the documents are concerned. If a strong case has been made out for the production of the documents, and the court concludes that their disclosure would not really be detrimental to the public interest, an order for production will be made.
See also Sankey v Whitlam per Stephen J at 63 - 64 and per Mason J at 98 - 99.
(5)When carrying out this balancing task, the court will give weight to the Minister's opinion that the documents should not be produced but will form its own opinion whether the public interest will be the better served by production or non-production: Sankey v Whitlam at 44-45, 96.
(6)Those who urge privilege on the ground of public interest immunity for classes of documents, regardless of particular contents, carry a heavy burden: Sankey v Whitlam per Stephen J at 62; see also Lord Reid in Rogers v Home Secretary [1973] AC 388 at 400. Speaking generally, a claim of public interest immunity for a class of documents will be upheld only if it is really necessary in the public interest or for the proper functioning of the public service to withhold the documents from production: Sankey v Whitlam at 39.
(7) … [T]here can be no single rule of thumb by which to determine whether a document should be produced for inspection … The fundamental principle is that documents may be withheld from production only if, and to the extent that, the public interest renders it necessary …
(8)It is a corollary of the general rule stated in proposition (1) that a court may intervene and prevent disclosure of a document whose production would be contrary to the public interest even if no claim is made by a Minister or other high official that its production should be withheld. The court has a duty to prevent disclosure without the intervention of any Minister if possible serious injury to the national interest is readily apparent: Sankey v Whitlam at 44, 58-59. However, it would be exceptional for the court to intervene where the Minister had considered the question and decided that no objection should be taken: Sankey v Whitlam at 44-45.
(9)It is now beyond question that the court has power to inspect the document or documents privately: Sankey v Whitlam at 46. There is, however, a question whether the court should look at the documents for assistance in the balancing exercise, that is to say, when weighing the two conflicting aspects of the public interest. In some cases, the court might be able to determine that the public interest requires that the documents be withheld from production without inspection of the documents: see Commonwealth v Northern Land Council … Only in cases where the ministerial affidavit demonstrates with sufficient particularity the nature and the significance of the documents both in terms of any need to preserve their confidentiality on the one hand and for the actual litigation on the other is it likely that it will be possible to reach such a conclusion: cf Woodhouse P in Fletcher Timber Ltd v Attorney-General at 295. In almost all other cases, an inspection will be necessary. There is a question whether the applicant for production of the document must satisfy some threshold test before the court inspects the documents. Plainly, the documents must be relevant. The question is whether any further or more stringent test is necessary. That question was examined by Gibbs CJ in Alister v The Queen (1984) 154 CLR 404, by Cox J in Legal Services Commission v Trotter at 84-85, and by Toohey J in the dissenting judgment in Commonwealth Northern Land Council at 632-363. Reference should also be made to Conway v Rimmer, Burmah Oil Co Ltd v Bank of England; Air Canada v Secretary of State for Trade; Fletcher Timber Ltd v Attorney-General; and Middleton v State of Western Australia. As Toohey J pointed out in Commonwealth v Northern Land Council at 634-635, the process of discovery (in this court, the list of documents) demonstrates the existence and relevance of the documents to the issues in the action. The application for production for inspection is a usual concomitant of the process of discovery. It would seem, therefore, that where there is a claim for privilege on the ground of public interest immunity, the court should without more inspect the documents for the purpose of weighing the competing public interests…
(10)Once a court has decided … that on balance the document should probably be produced, it will sometimes be desirable, or indeed essential, to examine the document before making an order for production: Sankey v Whitlam at 46 approving Conway v Rimmer … In addition, it seems prudent to inspect, first, to ascertain whether the relevance of any document is so peripheral that it should not be disclosed and, secondly, to determine whether, despite the fact that production should be ordered, it is necessary to mask part of the document: see para (12) below.
(11)If inspection of documents is necessary, it ought to be carried out by the court and not by any other person before ordering production for inspection …
(12)In some cases inspection may indicate that it is appropriate to order disclosure but that part of the document should be masked so as not to disclose something which the public interest requires should not be published. The practice was approved in Conway v Rimmer by Lord Reid at 943-944, 946-950 and by Lord Pearce at 988 and in Sankey v Whitlam by Gibbs ACJ at 48 and by Aickin J at 109-110.

Before the balancing task or exercise need be undertaken, the court must first be satisfied of the threshold question, namely, whether the party resisting the disclosure of documents has demonstrated the existence of a recognisable public interest in the documents requiring protection.[6]
[6] Royal Women’s Hospital v Medical Practitioners Board of Victoria [2006] VSCA 85 at [17] and [35], (2006) 15 VR 22 at 27 and 31; Kirby v Prisoners Review Board (No. 2) [2010] WASC 280 at [5] – [6].
The appellant submits that the Master erred in undertaking the required balancing exercise. It submits that having found the identities of the interviewees were relevant for the purpose of the rules of disclosure, the Court had to weigh the probative value of that information against the harm that is likely to be suffered to the public interest by the disclosure of the documents. It submits that the Master did not do this. The appellant called in aid the judgment of the Court of Appeal of Western Australia in The Australian Statistician v Leighton Contractors Pty Ltd[7] (“the ABS case”). In the ABS case, the Court of Appeal allowed an appeal from a judgment rejecting a claim of public interest immunity over documents prepared by the Australian Bureau of Statistics (“ABS”) in undertaking surveys for the purpose of preparing a statistical index in relation to changes in the price of building materials. The Court of Appeal held that the confidentiality of the commercially sensitive information obtained in interviews conducted on a promise that the information would be held in confidence should be maintained. It did so on the basis that confidentiality was necessary to ensure the voluntary cooperation of survey respondents in the future, the reliability of the information provided and its provision in a timely manner. Unrestricted disclosure of the information for the purpose of litigation had a significant potential to damage seriously the work of the ABS in the collection of reliable raw data in a timely manner for the preparation of price indices. This would impair the efficient functioning of the government in the management of the economy and had a sufficient connection with governmental function so as to attract public interest immunity.[8] The appellant submits that similar considerations in this case compel the same result.
[7] [2008] WASCA 34, (2008) 36 WAR 83.
[8] [2008] WASCA 34 at [42], (2008) 36 WAR 83 at 92.
The respondent submits that the appellant has failed to establish a proper evidentiary basis for its claim for public interest immunity in respect of the identities of the interviewees. In any event, he submits that the information set out in the documents concerns the fairly mundane topic of the interviewees eating habits over the period of one week. The respondent has no objection to any non-relevant medical information being redacted from the documents. Any suggestion that infected persons would be afraid to provide similar information at a later date if they understood there was a risk that their identity would be disclosed was fanciful. Even if it was, the work of the CDCB would be unlikely to be inhibited as medical practitioners are under a statutory obligation to notify the CDCB of the occurrence of communicable diseases such as salmonella. He submits that the ABS case is clearly distinguishable because the information in that case was confidential trade information that would tend to identify the persons who provided it, they were part of a limited class who might be expected to be asked to provide similar information at a later date, and accordingly, they required a clear and unqualified assurance that the information they provided would be absolutely protected. In addition, he submits that the ABS operates under stricter conditions as to the disclosure of identifying information than the CDCB.
The appellant relies upon the evidence of Dr Ann Patrice Koehler in support of its claim of public interest immunity. Dr Koehler is the Director of the CDCB. Her affidavit described the policy considerations for the maintenance of confidentiality of information provided to the CDCB by persons who contract communicable diseases. She said:[9]
In 2011 the CDCB worked within the parameters of The Public and Environmental Health Act (1987) which provides that personal information collected in the course of administering the legislation shall remain confidential. The policy reason for maintaining confidentiality is it serves the public interest in the administration of maintaining public health by facilitating freedom of disclosure of personal information between the sick person and the department. Protecting this personal information promotes full and frank disclosure by sick people to the department without the apprehension of being prejudiced by subsequent disclosure of that information. Sick people may refrain from seeking medical attention or reporting illness if personal information is not protected from disclosure. The effect of the failure to seek treatment for disease, or an inaccurate report of disease, is that CDCB will be unable to detect disease outbreaks adequately and the health and safety of the public will be threatened. If people feel free to provide details about their illnesses, contacts, and possible sources of the illness knowing that these will be treated confidentially, it enables the CDCB to gather the information necessary to take measures to protect the community from further outbreaks of the disease.
[9] Affidavit of Dr Ann Patrice Koehler affirmed 31 May 2013.
She describes the process by which these people are interviewed by officers of the Department of Health including the promise of confidentiality given to the interviewees. She asserts that it is necessary for the performance of the work of the CDCB that persons who contract communicable diseases cooperate readily and speedily with the Department of Health. To that end, it is important such persons have confidence that the confidentiality of information they provide to the Department of Health, for the purpose of identifying the source of an outbreak of communicable disease, is maintained to facilitate the work of the CDCB.[10]
[10] Affidavit of Dr Ann Patrice Koehler affirmed 31 May 2013.
Recent authority[11] emphasises that in order to sustain a claim of public interest immunity, the claimant must adduce evidence of sufficient cogency to establish a demonstrable necessity in the preservation of the confidentiality of particular information in the possession of a governmental agency. Nonetheless, as the reasons of Martin CJ in Kirby v Prisoners’ Review Board (No. 2) demonstrates, the relevant evidentiary threshold can be met inferentially from the nature of the documents which are the subject of the claim.[12]
[11] State of Victoria v Brazel [2008] VSCA 37, (2008) 19 VR 553; Kirby v Prisoners’ Review Board (No. 2) [2010] WASC 280.
[12] [2010] WASC 280 at [36] – [37].
There can be little doubt as to the importance of the work of the CDCB. The outbreak of communicable diseases in the community can pose a serious and significant risk to public health. The necessity to identify the source of an outbreak of communicable disease for the purpose of controlling the outbreak often requires that the work of the CDCB be undertaken with great urgency. I am satisfied that an important aspect of the work of the CDCB is interviewing persons who have contracted a communicable disease for the purposes of identifying, inter alia, the source of the infection or contamination. In my view, there is no reason not to accept the assertion by Dr Koehler that it is important to the CDCB’s work in this regard that it can provide an assurance to such persons that the information they provide, some of which they may consider to be mundane, some of which they may consider to be sensitive, is kept confidential. I accept that the promise of confidentiality given by officers of the Department of Health in undertaking this work is an important aspect of the efficacious performance of that work. In my view, the evidence of Dr Koehler is sufficient to establish the relevant public interest for the purposes of the claim of public interest immunity.
That threshold having been met, the question arises of balancing the competing interests between maintaining the identified public interest in the confidentiality of the personal information of the interviewees and the public interest in the administration of justice not being frustrated by the withholding of relevant evidence. In undertaking the balancing exercise, the court has to consider the nature of the damage which the work of the CDCB would be likely to suffer and the evidentiary value and importance of the information for which immunity is claimed in the particular litigation.[13]
[13] Alister v The Queen (1983 – 84) 154 CLR 404 per Gibbs CJ at 412; Australian Statistician v Leighton Contractors Pty Ltd [2008] WASCA 34 at [57], (2008) 36 WAR 83 at 95.
In order to undertake the balancing exercise in this case, it is unnecessary to inspect the documents. The relevant information sought to be protected is limited to information identifying the interviewees.
In my view, the Master erred in the approach he took to the balancing exercise. The Master failed to direct his attention to the threat posed to the ability of the CDCB to obtain cooperation in future from infected persons in the provision of vital information concerning the outbreak of communicable disease where they could not be assured that their identities and the information they provided would be kept confidential. The Master confined his consideration to the particular information contained in the documents regarding the interviewees eating patterns. He drew an inference as to whether they would have any particular objection to that information and their contact details being made available to the respondent in the circumstances of this matter.
The proper undertaking of the balancing exercise required the Court to adopt the approach of the Court of Appeal in the ABS case. That required consideration of the class aspect of the claim for public interest immunity and the associated public interest in issue. Like the Court of Appeal in the ABS case, the Master should have considered whether individuals who have contracted a communicable disease might be deterred from cooperating with the CDCB in a timely manner for the purposes of identifying the source of an outbreak if they knew there was a chance that their identity and the information they provided to the CDCB in that regard might be disclosed to the party who was suspected of causing the infection or contamination. Further, in my view, the Master erred in relying upon his assessment of the information provided by the interviewees in this case being of a mundane nature. Again, this approach overlooked the class aspect of the claim in favour of an exclusive focus on the contents of these particular documents.[14] The inquiries that might be made of a person who has contracted a communicable disease by the CDCB could be of a sensitive nature or at least involve an inquiry into topics that the interviewee subjectively considered to be sensitive. The knowledge that his or her identity might be disclosed to the party suspected of being responsible for the infection or contamination might have a chilling effect on persons who in future the CDCB would need to interview for the purpose of identifying the source of an outbreak of a communicable disease. In that context it must be borne in mind that the CDCB would have to explain to a person suffering from a communicable disease that an absolute assurance of confidentiality could not be given before the interview proper commences. Potential respondents will not know in advance whether they would regard the information sought in the interview to be innocuous or sensitive. I am prepared to infer that some persons in that position would be deterred from proceeding with the interview. The relevant public interest sought to be protected by the appellant involves the claim that the performance by the CDCB of its function in the protection the of public’s health will be harmed unless the CDCB can preserve the confidentiality of the identity of persons who have contracted communicable diseases and provided information to it concerning the contraction of the disease. For the purposes of undertaking the balancing exercise, what is relevant is, as the Court of Appeal in the ABS case said, the perception of the respondent community as a whole to the knowledge that having provided information relevant to ascertaining the source of an outbreak of disease their identities might not be kept confidential.[15]
[14] R v Young [1999] NSWCCA 166 at [152], (1999) 46 NSWLR 681 at 709 – 710.
[15] [2008] WASCA 34 at [60], (2008) 36 WAR 83 at 96.
I reject the respondent’s submission that the ABS case is distinguishable.
A comparison of the respective Acts under which the CDCB operates and has operated in the past,[16] and the Census and Statistics Act 1905 (Cth) under which the Australian Statistician and the ABS operate, discloses no obvious point of distinction in relation to the restrictions each agency operates under in respect to the disclosure of identifying information. While the information sought from interviewees by the CDCB is different in nature from the confidential trade information sought by the ABS, what is important is the subjective perception of the interviewees as to the sensitivity of that information in the event that the interviewees were identified as the source of the information in general as opposed to the specifics of the particular case here. This renders of comparable importance the need to assure any person being interviewed either by the ABS or the CDCB that the information they provide would be kept confidential. Finally, in my view, the relevant public interest is not diminished in this case by the fact that interviewees who have contracted a communicable disease are unlikely to be the subject of subsequent surveys as might have been the position in the ABS case. It is important to recognise that the process by which the information in the relevant documents was obtained was voluntary. If the CDCB is obliged to warn persons suffering from a communicable disease that their identity and the information they provide concerning their conduct could be disclosed to the party who might be responsible for the outbreak of that disease, I am satisfied that could deter some of those persons from giving the cooperation the CDCB needs to perform its work. It is not an answer to the problem to point, as the respondent does, to the statutory obligation imposed on medical practitioners compelling them to report notifiable diseases.[17] That statutory provision assists public health authorities in identifying the existence of a notifiable disease, not its source. Identification of the source of the outbreak of a notifiable or communicable disease depends, at least in part, on the CDCB’s work interviewing those who have contracted such diseases.
[16] Public and Environmental Health Act 1987 (SA) s 42 and s 42A; South Australian Public Health Act 2011 (SA) s 99 and s 100.
[17] Currently the South Australian Public Health Act 2011 (SA) s 64 and South Australian Public Health (Notifiable and Controlled Notifiable Conditions) Regulations r 4. Previously, and in particular, in or around January 2011 the Public and Environmental Health Act1987 (SA) s 30 and Schedule 2.
Being satisfied that the Master erred in the approach taken to the balancing exercise, it is open to the Court to undertake the balancing exercise for itself to determine the appellant’s claim for public interest immunity.
The importance of the redacted information to the conduct of the litigation is a relevant factor. As I have found, the redacted information is relevant to the issues in the litigation. However, it is far from clear that its relevance is significant. The litigation is concerned with the vindication of the respondent’s commercial reputation. While I have rejected the appellant’s submission that the respondent is engaged in a fishing expedition in seeking the redacted information for the purpose of determining the question of relevance, it is true nonetheless that there is no evidentiary material to which the respondent can point presently to suggest that the methodology adopted by the appellant in conducting the interviews was flawed. Against that, I must weigh the potential risk to the public interest that disclosure of the identity of the interviewees poses.
The potential for harm to the public interest that would result from disclosure of information identifying the interviewees who provide information to the CDCB outweighs the public interest in this litigation of the respondent obtaining the information which would permit it to identify the interviewees for the purposes of testing their recorded responses to the surveys relied upon by the appellant in making the impugned publications. I reach this conclusion on the basis that the disclosure ordered has the potential to affect adversely the work of the CDCB in establishing the source of an outbreak of communicable disease and the work of the Department of Health in combating such outbreaks. This conclusion is sufficient to allow the appeal. However, I should address one further argument put by the respondent.
The respondent submits that the appellant’s argument elevates its claim for public interest immunity to something analogous to the public interest immunity recognised in the protection given to police informers. I do not accept that is the effect of the claim for public interest immunity made in this case. Nonetheless, the authorities are instructive. They demonstrate that the immunity granted to police informers in protection of the public interest has been extended to other categories of informants.
In Rogers v Home Secretary[18] the immunity was extended to a situation where a person who had been refused a certificate from the Gaming Board sought production of a letter written about him to the Board by the Assistant Chief Constable of the County. The House of Lords said that the same considerations that applied to police informers must apply to those who volunteer information to the Board.[19] In D v National Society of for the Prevention of Cruelty to Children[20] the rule was extended by direct analogy to the relationship between the Society and ordinary persons volunteering information and lodging complaints with the Society. A false report had been made by a person to the Society alleging that D had been guilty of cruelty to her 14-month old daughter. An inspector of the Society called at D’s home to inspect the child. The mother claimed to have suffered severe and continuing nervous shock and brought action against the Society claiming damages for negligence. She sought to obtain the identity of the informant in order to join that person to the action against the Society. The House of Lords held that immunity from disclosure similar to that which the law allowed police informers should be extended to those who gave information about neglect or ill-treatment of children to the Society.
[18] [1973] AC 388.
[19] [1973] AC 388 per Lord Reid at 401.
[20] [1978] AC 171.
While Australian authorities suggest that the broad view of the operation of the doctrine of public interest immunity adopted in England may not apply here,[21] nonetheless similar considerations as were found persuasive by the House of Lords to invoke the doctrine support the conclusion that the claim for public interest immunity should be upheld in the circumstances of this case.
[21] Royal Women’s Hospital v Medical Practitioners Board of Victoria [2006] VSCA 85 per Charles JA at [109] – [116]; R v Young (1999) 46 NSWLR 681.
Conclusion

I would allow the appeal. I would set aside the orders of the Master made on 29 August 2013. I would hear the parties as to the question of costs.