In R. v. Barros, 2011 SCC 51, handed down yesterday, the Supreme Court ruled on whether the defence in a criminal matter is bound by the "informer privilege," deciding that it is not so bound.
Mr Justice Binnie wrote the judgment for the 7 in the majority, and on the broad point just stated his first paragraph says it all:
The jurisprudence establishes that the identity of police informers is protected by a near-absolute privilege that overrides the Crown’s general duty of disclosure to the defence. This privilege is subject neither to judicial discretion nor any balancing of competing interests (although qualified by an “innocence at stake” exception). The trial judge held however that this privilege does not restrict a defence investigation into the identity of a police informant, and further, that the attempt to fetter such a defence investigation would violate the constitutional right of an accused to a full answer and defence guaranteed by s. 7 of the Canadian Charter of Rights and Freedoms. A majority of the Alberta Court of Appeal disagreed. In its view, on the contrary, informer’s privilege prohibits the accused or anyone on his behalf from making efforts even wholly independent of the prosecution to discover which of his associates, if any, had “ratted” on him. This proposed extension of the rule would transform a rule of non-disclosure binding on the police, the prosecutorial authorities and the courts into a general prohibition of investigation into police informers binding on the whole world. In my view, with respect, this goes too far.
This is a case involving a private eye, a "rat," allegations of extortion and obstruction of justice — very much the stuff of detective novels. But my knowledge of criminal law is utterly non-existent, so I'll leave it to others to explore the judgment on Slaw if they wish. (I'm embarrassed to admit that I had no idea that there was an "informer privilege," a law that at first blush strikes me as unsavoury, regardless of any instrumentality it may have.)