(2) The relevant legal principles
35 The principles to be applied were summarised by Gibbs ACJ in Sankey v Whitlam [1978] HCA 43; (1978) 142 CLR 1 at 38-39 in the following terms:
The general rule is that the 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. However the public interest has two aspects which may conflict. These were described by Lord Reid in Conway v. Rimmer, as follows:
'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.'
It is in all cases the duty of the court, and not the privilege of the executive government, to decide whether a document will be produced or may be withheld. The court must decide which aspect of the public interest predominates, or in other words whether the public interest which requires that the document should not be produced outweighs the public interest that a court of justice in performing its functions should not be denied access to relevant evidence. In some cases, therefore, the court must weigh the one competing aspect of the public interest against the other, and decide where the balance lies. In other cases, however, as Lord Reid said in Conway v. Rimmer, 'the nature of the injury which would or might be done to the nation or the public service is of so grave a character that no other interest, public or private, can be allowed to prevail over it'. In such cases once the court has decided that 'to order production of the document in evidence would put the interest of the state in jeopardy', it must decline to order production.
36 The IGADF bears the burden of establishing a claim to public interest immunity. It has been said that to establish such a claim 'involves a heavy burden' that requires the party claiming the immunity to demonstrate a real detriment to the public interest from disclosure: Somerville v Australian Securities Commission (1995) 60 FCR 319 at 354 (Lindgren J) applied in Cadbury Schweppes Pty Ltd v Amcor Limited [2008] FCA 88 at [26] (Gordon J). I take such statements to emphasise the need to demonstrate a public interest of a kind that means there is a real risk that it would be harmed if complete secrecy in respect of particular information was not maintained and protected.
37 There have been a number of instances in which the harm that would result if the confidentiality of an investigative process was compromised by requiring documents to be produced before the investigative process has been concluded has been found to give rise to a sufficient public interest for the purposes of a claim of public interest immunity.
38 In National Companies and Securities Commission v The News Corporation Limited [1984] HCA 29; (1984) 156 CLR 296, Mason, Wilson and Dawson JJ recognised that in the exercise of statutory powers which allowed the Commission to hold public or private hearings for the purpose of investigating whether a person had committed an offence, it was consistent with meeting a requirement to afford natural justice for the Commission to conduct part of the process without the presence of legal representatives of News Corporation, being an entity whose conduct was being investigated. Their Honours said at 323-324:
It is of the very nature of an investigation that the investigator proceeds to gather relevant information from as wide a range of sources as possible without the suspect looking over his shoulder all the time to see how the inquiry is going. For an investigator to disclose his hand prematurely will not only alert the suspect to the progress of the investigation but may well close off other sources of inquiry. Of course, there comes a time in the usual run of cases when the investigator will seek explanations from the suspect himself and for that purpose will disclose the information that appears to require some comment. Having regard to the express statutory injunction of s. 38(l)(d) of the N.C.S.C. Act, it would clearly be a denial of natural justice if the Commission in the present hearing received evidence adverse to News Corporation without providing an opportunity to News Corporation to be heard. An effective examination of such persons would require that the substance of the adverse information received during the investigation be disclosed to them.
39 In Spargos Mining NL v Standard Chartered Australia Ltd (No 1) (1989) 8 ACLC 87 at 87-88, McLelland J held that:
In my opinion, documents within the possession of the Commission of a confidential nature recording information received by the Commission relating to possible offences or irregularities, or recording information received in the course of the investigation of possible offences or irregularities, including the identity of informants, and confidential documents recording the actual or possible course of such investigations or particulars of available or potentially available evidence, are in the public interest prima facie immune from compulsory disclosure, on the basis that such disclosure could be likely to seriously impede the ability of the Commission to fulfil its function of effectively investigating possible offences under, inter alia, the Companies (NSW) Code, and in appropriate cases instituting and prosecuting criminal or civil proceedings in the public interest.
40 In doing so, his Honour reasoned by reference to the observations in National Companies and Securities Commission v The News Corporation Ltd that have already been quoted.
41 In Criminal Justice Commission v Collins (1994) 74 A Crim R 63, the Court considered whether material obtained by the Commission in investigating a complaint alleging misconduct against certain police officers should be produced for the purposes of criminal proceedings that had been preferred at the instance of one of the officers. In considering a claim to public interest immunity, Macrossan CJ and McPherson JA said at 66:
It may be accepted that statutory bodies with functions like those of this Commission must have some necessary degree of immunity if they are to function as intended, but, when a claim is made by such bodies for protection from the ordinary processes of the courts and the claim is disputed it is the courts who will make the necessary decision. They will do so by considering the terms of relevant constituent statutes and by giving attention to relevant public policy considerations. The court's decision will involve a balancing exercise once it has been decided that a public policy entitlement to protection exists. At this point the policy need for protection of the due functioning of the body's process will be balanced against the conflicting need to ensure that the demands of justice are served with protection offered to the individual rights involved. This balancing exercise has been described as a two-stage process. At the first stage the concern is to determine whether a valid claim to public policy immunity arises by reason of the intended statutory function of the body on whom the demand for disclosure is made and then, in the particular circumstances of the case, there follows a weighing of the relative strength of that need and the competing need for reasons of justice to give access to the information which is sought: Sankey v Whitlam (1978) 142 CLR 1; Alister (1984) 154 CLR 404 …
The exercise which the examining court must undertake reflects the fact that claims to immunity are not automatically acceded to, but will be made subject to judicial assessment. It will be necessary for the body claiming immunity from disclosure to demonstrate the need for protection which its statutory function requires and establish the strength of that need in the particular case: cf Mason J in Sankey v Whitlam (at 96).
42 In Attorney-General (NSW) v Stuart at 675, Hunt CJ described a broader public interest in respect of the production of information that would frustrate or impede the police in undertaking their inquiries.
43 In Goldberg v Ng (1994) 33 NSWLR 639, documents held by a Law Society were sought by subpoena. The Court rejected the proposition that public interest immunity applies to documents provided by a solicitor to a Law Society in response to a complaint against the solicitor. Significant to that conclusion was the absence of any provision in the relevant legislation regulating the profession providing any assurance of confidentiality or immunity from disclosure of information provided in respect of investigations by the Law Society: at 647-648 (Kirby P), 678 (Clarke JA). Also of significance was the way in which the claim to immunity was put. It was said to be required to protect the candour with which responses would be given to the Law Society by lawyers whose conduct was called into question. It was not a claim that there should be immunity to protect a process that was designed to secure disclosure of deficiencies or impropriety by those who might otherwise be discouraged from making complaint. It was found that confidentiality did not aid the performance of the particular responsibilities of lawyers to provide information frankly and candidly where their conduct was criticised. Therefore, as to the nature of the basis for the claim to public interest immunity, the case must be distinguished from the present instance.
44 In Australian Securities and Investments Commission v P Dawson Nominees Pty Ltd [2008] FCAFC 123; (2008) 169 FCR 227, the Court was concerned with a claim of public interest immunity in respect of information that would identify certain informers who had provided information to the Commission. The Court had regard to the fact that the Corporations Act 2001 (Cth) included provisions providing protection for whistleblowers. In that context, it was observed that '[t]he common law doctrine of public interest immunity should be applied consistently with the legislative policy manifest in [the whistleblower provisions] in the particular case of disclosures to [the Commission]': at [38]. However, the Court did not advance that proposition as a reason why a claim to immunity should be upheld. Rather, it was expressed as a reason why the common law should recognise a public interest in non-disclosure for the purposes of the application of the doctrine of public interest immunity, including by weighing the competing public interests.
45 There have also been instances in which the need to protect the identity of informers has provided a basis for a claim to immunity: R v Meissner (1994) 76 A Crim R 81; Australian Competition and Consumer Commission v Prysmian Cavi E Sistemi Energia S.R.L. [2011] FCA 938 at [194]-[195] (Lander J); Attorney-General (NSW) v Stuart at 674-676; Cain v Glass (No 2) (1985) 3 NSWLR 230 at 247-248 (McHugh JA); and Attorney General (NSW) v Lipton [2012] NSWCCA 156.
46 However, a claim to immunity to protect information provided by informers in all likelihood does not extend to an instance where the informant acted without any assurance of confidentiality: Cadbury Schweppes at [29].
47 In any case, where there is a public interest of the requisite character that would be injured by disclosure, then there must be real risk of harm to that interest: The Australian Statistician v Leighton Contractors Pty Ltd [2008] WASCA 34; (2008) 36 WAR 83 at [46]. The risk of harm to public interest must be of a kind that has been shown to require complete, not partial secrecy in order for the risk to be averted: at [41]. If such an interest is demonstrated, then in balancing the competing public interest concerned with ensuring that the due administration of justice is not frustrated, the Court may take into account the possibility that orders may be tailored in a way that would limit any harm to the public interest supporting the public interest immunity claim.
48 In P Dawson Nominees, in considering the balancing exercise, the Court noted that the public interest in protecting informers, and encouraging future informers, was as important to a regulatory agency such as the Commission as it is to the police in their traditional role: at [48]. The potential effect on future informers of disclosure was identified as a matter that 'carries great weight' in the balancing process that forms part of considering whether public interest immunity applied: at [51].
49 The nature of the three stage test means that it is important to identify the particular respect in which the administration of justice would be frustrated if the information remained secret. In order to show damage or impairment to the court process it must be shown that the information is material and, as has been already noted, that there is a legitimate forensic purpose to which the information may be put in the proceedings: Attorney-General (NSW) v Stuart at 681. In the decided cases that task is usually undertaken by seeking to identify the evidentiary significance of the information given the nature of the issues in the proceedings. However, in Gypsy Jokers Motorcycle Club Incorporated v Commissioner of Police [2008] HCA 4; (2008) 234 CLR 532 at [24], Gummow, Hayne, Heydon and Kiefel JJ described the consequence of upholding a claim to public interest immunity as being that 'the material was not admitted into evidence and would be denied both to the Court and the applicant'. Expressed in those terms, the consequence as described appears to embrace the need to consider the potential for the wider forensic use of the information in the proceedings, such as to indicate a line of inquiry or to expose matters that might bear upon the credibility of a particular account. The cases do not indicate that the public interest in the administration of justice is confined to a concern as to whether the information may be admitted into evidence. It is well established that public interest immunity is a substantive principle of common law and is not simply a rule of evidence: Commissioner of Police, New South Wales v Guo [2016] FCAFC 62 at [6]-[14] (Collier J), [61] (Robertson and Griffiths JJ).
50 In undertaking the balancing exercise in P Dawson Nominees, the Court posed the question as to what should be weighed in the balance in favour of disclosure by asking what disadvantage the party seeking disclosure would suffer in its litigation by not getting access to the documents in question: at [53]. The Court reached the following conclusion in relation to that question (at [61]):
In the circumstances of this case, we do not see the documents in question as having sufficient importance for PDN's conduct of this litigation to outweigh the importance of not disclosing the identity of informers. The documents may be discoverable, and relevant, but beyond that they are not shown to have any greater significance for PDN.
51 In R v Meissner, Carruthers J (Smart J agreeing) considered various formulations of the way the balancing task should be undertaken: at 87-88. In upholding the claim to immunity his Honour put the matter in terms that it could not be concluded that non-disclosure may amount to 'substantial prejudice' to the appellant's defence of criminal proceedings and the case amounted to no more that 'the speculative possibility' that the material provided by informers (that would disclose their identity) may expose discrepancies in the Crown case. In Von Snarski v Criminal Justice Commission [1998] 1 Qd R 562, where documents the subject of an immunity claim by the Commission were sought by an accused person in criminal proceedings it was said that '[u]nless there is some likelihood that the documents will materially assist the defence it is unnecessary to embark upon any … balancing exercise': at 564 (Pincus and Davies JJ).