The duty to protect and enforce informer privilege rests on the police, the Crown, and the courts. The latter must not disclose any information that would tend to reveal an informer’s identity.
However, the defence is not bound by any such duty in undertaking its own investigation independently of the courts and the prosecution. The defence is entitled to do what it can to identify the informant and otherwise make full answer and defence, provided that the methods used are lawful. The right to make full answer and defence is fundamental to criminal justice and is protected by s. 7 of the Charter. However, not all attempts to identify an informant will be linked to that right.
It will depend on the circumstances. Some defence enquiries may amount to an obstruction of justice, or extortion, depending on the manner in which the enquiries are carried out and their intended purpose, and the other circumstances of the case.
Source: R. v. Barros, 2011 SCC 51
