Public Interest Immunity

What is Public Interest Immunity? 

During the course of an investigation, the police may come into possession of sensitive material. This material may potentially be reasonably considered capable of undermining the case for the prosecution against the accused and/or of assisting the case for the accused. Nonetheless it may be withheld by the Crown under the “public interest immunity” (“PII”) principles.

An application for PII made by the prosecution must be heard and decided upon by the court. if the court orders that the prosecution do not have to disclose material to the defence, the defence may challenge that decision and the court may then either uphold its original ruling or order disclosure pursuant to the defence application. Issues relating to PII arise in both the magistrates’ court and the Crown Court.

The statutory provisions and codes in this area are as follows:

  • Criminal Procedure and Investigations Act 1996 (CPIA 1996);

  • The Criminal Procedure Rules 2005, Part 25;

  • Disclosure: Court of Appeal protocol for the control and management of unused material in the Crown Court.

  • Attorney-General’s Guidelines: Disclosure of Information in Criminal Proceedings.

Non-Disclosure on Public Policy Grounds

A conflict exists between the general principle that the administration of justice requires that the defendant should have full access to all non-privileged, relevant material and the doctrine that provides that certain material may be withheld if it is not in the public interest to disclose it.

Material may only be withheld on the basis that a successful claim of PII has been made by the party seeking to prevent disclosure.

The test for disclosure where public interest immunity is claimed 

The CPIA  1996 s.21(1) abolished the old common law rules in relation to the prosecution duty of disclosure and put in its place a new statutory framework. S. 3(6) (in relation to initial disclosure) and s.7A(8) (in relation to the prosecutor’s continuing duty) state that “material must not be disclosed…to the extent that the court, on an application by the prosecutor, concludes it is not in the public interest to disclose it and orders accordingly.”           

The main categories of sensitive material:

  • National security/Affairs and interests of state

  • Journalists’ sources

  • The prevention, detection & investigation of crime

  • Material relating to children or young children

These are just the most commonly occurring examples and thus this list should not be regarded as exhaustive. It is also important to remember that each case turns on its own facts and even cases involving the same type of documents may result in different disclosure decisions.

National security/Affairs and interests of state

A claim may be justified on the grounds that disclosure of material be prejudicial to national security. The test is whether disclosure would cause real harm to the public interest. Where the government minister is advised that disclosure of the document would cause real harm or a threat to national security, s/he is obliged to sign a PII certificate to that effect. Once the risk to national security has been certified by an appropriate ministerial certificate, the court should not exercise its right to inspect as the certificate will be conclusive.

Journalists’ sources

In summary, s.10 of the Contempt of Court Act 1981 provides that a court may not require a person to disclose any source of information contained in a publication unless the court is satisfied that it is in the interests of justice or national security or for the prevention of disorder or crime to order disclosure. In the absence of one of these criteria, a person cannot be held in contempt of court for refusing to disclose. 

The prevention, detection and investigation of crime

In criminal cases, the following categories are the ones that will be encountered most often:

  • Informers

It is established law that there is a clear public interest in protecting the identity of those who give information to the police. A ruling on this basis prevents the disclosure of any material that might lead to the identity of an informer being revealed.

There is an exception to this common-law rule, where the judge is of the opinion that disclosure is necessary to establish the innocence of the accused.

  • Police observation posts

The general principle as set out above extends to the protection of the identity of those persons who have allowed their premises to be used for the surveillance and, therefore, the principle further extends to the location of those premises or any material tending to identify the location or the owner’s identity. The principle is aimed to ensure the protection of such persons from harassment as well as violence.

  • Police reports, manuals and methods

Reports between police forces or between the force and the DPP/CPS are protected on the basis that there needs to be free access to information and ideas in order for the criminal investigation process to function properly. Similarly, manuals and descriptions of police methods dealing with (for example) crowd control, demonstrations and riots need to be protected so that police methods/tactics are not frustrated. The same principle and reasoning applies to other police methods of investigation.

  • Information relating to children


It is well established that various categories of documents and records maintained by social services and other agencies are protected by PII in order to safeguard the welfare of children.


Procedural considerations


Scheduling of sensitive unused material

The duty of the disclosure officer.  The disclosure officer must list on a schedule any sensitive material which he   believes it is not in the public interest to disclose, and the reason for that belief. The schedule must include a statement that the disclosure officer believes the material is sensitive. Once material is determined to be “sensitive”  it is listed on form MG6D. This document is a separate document to the schedule of non-sensitive unused material (MG6C) and is used to assist the prosecution. It is not disclosed to the defence.


Duties of the prosecutor

The prosecutor must review the schedules and make decisions as to what material would ordinarily be disclosed at either the prosecutor’s initial duty to disclose or under their continuing duty to disclose, in accordance with the different statutory tests contained in sections 3 and 7A of the CPIA 1996. Then the prosecutor must decide whether material, which otherwise would be disclosed pursuant to these tests, should not be disclosed on the grounds of public interest immunity-in other words that it would be against public policy to disclose it.


The procedural guidelines

Guidelines relating to how the prosecution should manage such applications were first laid down by the Court of Appeal in the appeal of R v Davis, Johnson and Rowe [1993] 2 All ER 643. The guidelines pre-date the introduction of the CPIA 1996 but the procedures were specifically retained by that Act.


The prosecution application

In situations when the defence are aware of the application being made, the defence can attend an inter parties hearing in open court, with the prosecutor present. At such a hearing, both the prosecution and defence are entitled to make representations to the court. However, in such cases, the court still considers the PII material ex parte with just the prosecution present.


The procedure for making a defence application for disclosure under the CPIA 1996

Section 8 of the CPIA 1996 provides that the defence can apply for a review of a non-disclosure order by the court. If the defence are unsuccessful at their first attempt, they can apply at any time prior to conviction or acquittal for a review.

Performing the “balancing exercise”

The balance is between the public interest to withhold and the interests of justice to disclose. If the disputed material MAY prove the defendant’s innocence or prevent a miscarriage of justice, then the balance comes down resoundingly in favour of disclosure of the defence. Therefore, if there is a chance that the information may lead to an acquittal, the judge should order disclosure.

What happens if disclosure is ordered?

The prosecution are then faced with a decision to either disclose the documents or to abandon the prosecution in order to continue to protect e.g. the identity of the informant.