Public Interest Privilege
Any information sought be be disclosed may be prohibited under s. 37 of the Evidence Act on "grounds of specified public interest". This can consist of a separate ground to prohibit the disclosure of informer or source information. However, most times it is dealt with by way of the common law.
Objection to disclosure of information
37 (1) Subject to sections 38 to 38.16, a Minister of the Crown in right of Canada or other official may object to the disclosure of information before a court, person or body with jurisdiction to compel the production of information by certifying orally or in writing to the court, person or body that the information should not be disclosed on the grounds of a specified public interest.
Obligation of court, person or body
(1.1) If an objection is made under subsection (1), the court, person or body shall ensure that the information is not disclosed other than in accordance with this Act.
Objection made to superior court
(2) If an objection to the disclosure of information is made before a superior court, that court may determine the objection.
Objection not made to superior court
(3) If an objection to the disclosure of information is made before a court, person or body other than a superior court, the objection may be determined, on application, by
- (a) the Federal Court, in the case of a person or body vested with power to compel production by or under an Act of Parliament if the person or body is not a court established under a law of a province; or
- (b) the trial division or trial court of the superior court of the province within which the court, person or body exercises its jurisdiction, in any other case.
(4) An application under subsection (3) shall be made within 10 days after the objection is made or within any further or lesser time that the court having jurisdiction to hear the application considers appropriate in the circumstances.
(4.1) Unless the court having jurisdiction to hear the application concludes that the disclosure of the information to which the objection was made under subsection (1) would encroach upon a specified public interest, the court may authorize by order the disclosure of the information.
(5) If the court having jurisdiction to hear the application concludes that the disclosure of the information to which the objection was made under subsection (1) would encroach upon a specified public interest, but that the public interest in disclosure outweighs in importance the specified public interest, the court may, by order, after considering both the public interest in disclosure and the form of and conditions to disclosure that are most likely to limit any encroachment upon the specified public interest resulting from disclosure, authorize the disclosure, subject to any conditions that the court considers appropriate, of all of the information, a part or summary of the information, or a written admission of facts relating to the information.
(6) If the court does not authorize disclosure under subsection (4.1) or (5), the court shall, by order, prohibit disclosure of the information.
(6.1) The court may receive into evidence anything that, in the opinion of the court, is reliable and appropriate, even if it would not otherwise be admissible under Canadian law, and may base its decision on that evidence.
When determination takes effect
(7) An order of the court that authorizes disclosure does not take effect until the time provided or granted to appeal the order has expired or, if the order is appealed, the time provided or granted to appeal a judgment of an appeal court that confirms the order has expired and no further appeal from a judgment that confirms the order is available.
Introduction into evidence
(8) A person who wishes to introduce into evidence material the disclosure of which is authorized under subsection (5), but who may not be able to do so by reason of the rules of admissibility that apply before the court, person or body with jurisdiction to compel the production of information, may request from the court having jurisdiction under subsection (2) or (3) an order permitting the introduction into evidence of the material in a form or subject to any conditions fixed by that court, as long as that form and those conditions comply with the order made under subsection (5).
(9) For the purpose of subsection (8), the court having jurisdiction under subsection (2) or (3) shall consider all the factors that would be relevant for a determination of admissibility before the court, person or body.
R.S., 1985, c. C-5, s. 37; 2001, c. 41, ss. 43, 140; 2002, c. 8, s. 183; 2013, c. 9, s. 17(E).
Section 37.3 permits the accused to apply for a stay of proceedings or dismissal of the charges where the prohibition orders under s. 37 affect the right to a fair trial:
Protection of right to a fair trial
37.3 (1) A judge presiding at a criminal trial or other criminal proceeding may make any order that he or she considers appropriate in the circumstances to protect the right of the accused to a fair trial, as long as that order complies with the terms of any order made under any of subsections 37(4.1) to (6) in relation to that trial or proceeding or any judgment made on appeal of an order made under any of those subsections.
(2) The orders that may be made under subsection (1) include, but are not limited to, the following orders:
- (a) an order dismissing specified counts of the indictment or information, or permitting the indictment or information to proceed only in respect of a lesser or included offence;
- (b) an order effecting a stay of the proceedings; and
- (c) an order finding against any party on any issue relating to information the disclosure of which is prohibited.
2001, c. 41, s. 43; 2015, c. 3, s. 14(F).
The following have been recognized as privileged as an investigative technique:
- simulated ingestion of controlled substances
- location of a surveillance or observation post
- the location of tracking devices
- the location and methods of examining of secondary VINs 
- R v Meuckon, 1990 CanLII 1766 (BC CA), (1990), 57 CCC (3d) 193 (BCCA)
- R v Lam 2000 BCCA 545 (CanLII), (2000), 148 CCC (3d) 379 (BCCA)
R v Richards 1997 CanLII 3364 (ON CA), (1997), 115 CCC (3d) 377 (Ont.C.A.)
- R v Guilbride, 2003 BCPC 176 (CanLII),  BCJ No.1245 (Prov.Ct.)
R v Boomer 2000 CanLII 4176 (NS SC), (2000), 182 N.S.R. (2d) 49 (S.C.)
R v Smith, 2009 ABPC 88 (CanLII)
Information Affecting National Security
This privilege in the context of ministerial documents is sometimes called "Cabinet Privilege" or "Ministerial Privilege".
Section 38.01 of the Canada Evidence Act imposes obligations on participants in proceedings to notify the Attorney General of Canada of any potential disclosure of information believed to be "sensitive" or "potentially injurious". Section 38.02 then imposes an obligation not to disclose the information. It is then for the Attorney General to decide what to disclose. Parties seeking disclosure can apply to the Federal Court for an order of disclosure.
see R v Clarke, 2015 NSSC 26 (CanLII) at para 28
Nova Scotia (Attorney General) v Royal & Sun Alliance Insurance Co. of Canada,  NSJ No. 404 at para 14
- see s. 38.3 and 38.031
- see s. 38.04 to 38.09 and 38.1 to 38.14
Parliamentary, Ministerial, and Cabinet Privilege
Section 39 protects information that is a "confidence of the Queen's Privy Council of Canada". This includes memos, discussion papers, agenda, deliberations, materials used to form decisions and policy (s. 39(2)) that is held by cabinet and parliamentary committees.(s. 39(3))
The onus is upon the government to establish a claim of cabinet privilege.
Nova Scotia (Attorney General) v Royal & Sun Alliance Insurance Co. of Canada, 2000 CanLII 1080 (NS SC),  NSJ No. 404 at para 15