Fact sheet public interest immunity

Issued: 25 August 2020

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Public Interest Immunity

Public interest immunity ("PII") is a common law doctrine and the name given to the body of substantive and procedural rules whereby confidential information that is otherwise relevant to court proceedings is withheld on the ground that the public interest in its disclosure is outweighed by a competing public interest in its suppression. The immunity applies to prevent the disclosure of information in a range of situations, including pursuant to a subpoena, discovery, or a call for a document in court and in the course of a witness giving evidence.[1]  

In proceedings in most NSW Courts, s. 130 of the Evidence Act 1995, which refers to "matters of state", applies PII principles to evidence being adduced. Section 131A operates to extend s. 130 to apply to pre-trial processes where a person objects to producing documents.

Categories of PII

PII applies to protect confidential information where disclosure would harm the public interest.  While the categories are not closed, s. 130(4) of the Evidence Act sets out a list of matters that can be taken to relate to PII/matters of state, being information which, if disclosed, would:

  • prejudice the security, defence or international relations of Australia; or
  • damage relations between the Commonwealth and a State or between 2 or more States; or
  • prejudice the prevention, investigation or prosecution of an offence; or
  • prejudice the prevention or investigation of, or the conduct of proceedings for recovery of civil penalties brought with respect to, other contraventions of the law; or
  • disclose, or enable a person to ascertain, the existence or identity of a confidential source of information relating to the enforcement or administration of a law of the Commonwealth or a State; or
  • prejudice the proper functioning of the government of the Commonwealth or a State.

Cabinet information

Confidential State papers such as Cabinet submissions, other Cabinet documents, and documents relating to the framing of government policy at a high level are subject to PII if disclosure or adduction of the information would prejudice the proper functioning of the government of the Commonwealth or a State.  

The actual deliberations of Cabinet and the decisions made by Cabinet are afforded the highest protection as their confidentiality supports the principle of collective responsibility and the uninhibited decision-making and policy development by Cabinet.  Cabinet documents which record the matters put to Cabinet for discussion (such as minutes or submissions for the consideration of Cabinet) are generally treated in the same position as records of the deliberations or decisions of Cabinet.[2]

Recognising that important issues of policy may be resolved below the level of Cabinet, non-Cabinet documents and communications regarding "the framing of government policy at a high level" or "important matters of policy" may also be protected by PII.[3] The public interest in preserving the secrecy of such documents may be given less weight in the balancing process than applies to Cabinet information, which is afforded a high level of protection.

The immunity of Cabinet information from disclosure is also not absolute, and there may be occasions where the court requires the disclosure of Cabinet information, particularly where it relates to the reporting on, and discussion, of the factual and legal aspects of a commercial dispute involving the State and is of substantial significance to the resolution of the dispute.[4]

Some examples of documents that may be the subject of such a PII claim are:

  • Records of Cabinet deliberations and decisions;[5] 
  • Cabinet submissions and minutes submitted to Cabinet for its consideration and documents created for the purpose of preparing a submission to Cabinet;[6]
  • Documents prepared for the purpose of providing advice to Cabinet or for the use of a Minister in Cabinet;
  • Documents, including communications between Ministers or between other senior government staff, that would disclose the content of Cabinet submissions, such as Ministerial briefing notes and Ministerial correspondence;[7]
  • Reports prepared by external experts for consideration by Cabinet; and
  • Other State papers where the documents are concerned with the framing of government policy at a high level.[8]

Disclosure of confidential sources

PII protects people who provide information or assistance to law enforcement and regulatory agencies on the basis that their identities will be kept confidential. This is to protect sources from retribution because of their assistance and to ensure the free flow of information to these agencies.  Not only are their identities protected, but also any information that would allow their identities to be ascertained, or which would identify them as the source of the information.

Prejudice to the prevention, investigation or prosecution of an offence

PII also protects from disclosure confidential information that would, or might:

  • reveal confidential methods of investigation undertaken by law enforemcent and regulatory agencies – so as not to allow those committing offences to circumvent such methods, for example, by carrying out counter-suveillance or tailoring their activities to avoid detection; and
  • allow a person committing, or who has committed, an offence to take steps to thwart an investigation, for example, by destroying inculpatory evidence, creating exculpatory evidence, manufacturing an alibi or fleeing the jurisdiction.

Evidence in support of a claim

A PII claim will be supported by affidavit evidence which demonstrates to the Court the harm that will be caused by disclosure.  Affidavit evidence must be sworn at the highest or close to the highest level in the agency, normally by the responsible Secretary or Deputy Secretary. This is because, first, the deponent is generally not permitted by the Court to be cross-examined on their affidavit. Secondly, the person swearing the affidavit evidence must be familiar with the workings of their agency at all levels, so as to be in a position to make assertions about the prejudice that may be caused by disclosure of the particular information.

Relevant government policies

PII is core legal work and must be referred to the Crown Solicitor.[9] The Crown Solicitor will provide advice including about whether material is subject to PII and will act for the relevant agency in relation to any claim.

Any process of discovery or subpoena relating to official Cabinet records must be brought to the attention of the Department of Premier and Cabinet before any decision regarding access is made.[10] In practice, this means that where an agency identifies official Cabinet records (or drafts thereof) contact should be made by the agency with the DPC Legal Branch immediately.

Any claim of PII must be approved by the Solicitor General or the Crown Advocate.[11] It is part of the role of the Crown Solicitor's Office to consult the Solicitor General or the Crown Advocate to obtain approval for the making of the claim.

[1] The immunity also applies outside court proceedings, such as to resist a search warrant: Jacobsen v Rogers (1994) 182 CLR 572

[2] Commonwealth v Northern Land Council [1993] HCA 24; 176 CLR 604

[3] Sankey v Whitlam (1978) 142 CLR 1 per Gibbs ACJ at 39 and Mason J at 99

[4] State of New South Wales v Public Transport Ticketing Corporation [2011] NSWCA 60

[5] Commonwealth Northern Land Council

[6] Lanyon Pty Ltd The Commonwealth (1974)  129 CLR 650

[7] Commonwealth v Construction, Forestry, Mining and Energy Union (2000) 98 FCR 31; 171 ALR 379; [2000] FCA 453

[8] Sankey v Whitlam

[9] Premier's Memorandum M2016-04: NSW Government Core Legal Work Guidelines

[10] Premier's Memorandum M1997-26: Litigation Involving Government Authorities

[11] Premier's Memorandum M1997-26: Litigation Involving Government Authorities


Penny Csenderits, Director
Community Law practice group
02 9474 9319

Anthea Tomlin, Special Counsel
Community Law practice group
02 9474 9260

Last updated:

16 Nov 2022

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