UK: Public interest immunity (feature)
01 May 1993
The 1992 Matrix-Churchill trial brought the clandestine "Boys' Own" world of the security services a bit further into the light of day. This was largely because of the efforts of defence lawyers in successfully arguing that hundreds of ministerial, departmental and Security and Intelligence Service (SIS, ie MI5 and MI6) documents should be made available to them. They revealed, as is now well-known, that agencies of government knew of, approved of and encouraged the sale of arms-making equipment to Iraq in the 1980s, and the exposure led to the acquittal of the defendants.
The prosecution had proceeded on the basis that the documents were "privileged" and not subject to the usual requirement that the prosecution ensure that all relevant material is made available to the defence. The "safe haven" into which the government, security services and prosecution tried to steer this vital material was public interest immunity (pii). Pii used to be termed "Crown privilege", but the term is no longer used, apparently because it is not necessarily only the Crown which asserts it, and ostensibly too because it is not supposed to be a privilege, but a duty, to protect sensitive material from disclosure. More cynical upholders of civil liberties might comment that this republican-style change of terminology owes more to George Orwell than to modernity or precision. The public must be protected from knowing about that which its servants and agents do in its name.
Pii has been a recognised legal concept for at least a century and a half. It is asserted to protect the interests of national security or diplomatic relations, or to protect the "integrity of communications" with or within a public department. National security considerations require little further explanation: to publish a list of MI5 operations might well be detrimental to its spying activities. Protecting inter- and intra-departmental communications is slightly more difficult to comprehend. The pii argument goes that ministers, policy advisers, civil servants,
police officers and other public servants would not communicate with the same frankness and candour, should there be a threat of exposure of their discussions in open court.
The court procedure
In principle, pii is a duty which must be asserted and cannot be waived, so that a prosecutor in possession of a document in a protected class without which he could not prove his case would, in theory, be bound to object to its disclosure in court, and let the defendant walk free. This situation has never occurred, although a prosecution based solely on protected documents would in all probability not proceed, and cases based solely on the evidence of informants whose identity (or existence) the prosecution do not want to disclose have on several occasions been abandoned. This happened to a number of cases involving football "gangs" infiltrated by undercover police officers.
Theoretically pii can be raised by any party or by the judge, but in practice it is almost always asserted by the issue of a public interest certificate signed by ministers or an affidavit claiming public interest, produced by the prosecution. If pii is asserted, the person seeking disclosure of the document must first prove that it is material to the case. This is not easy, since in all probability he has never seen it. Indeed, in most cases, including the Matrix-Churchill trial, not only the contents of such documents, but even their existence, is not known.
In the Glor na nGael case, the Northern Ireland Minister directed the withdrawal of funding from the West Belfast committee of the voluntary group after five years of funding, on the basis that after "security advice" was sought in relation to (unnamed) "persons understood to be prominent of the affairs of the committee", the Minister decided that there was a "grave risk that financial assistance would directly or indirectly assist a paramilitary organisation". The group challeng