R. v. Cook, 2014 ONCA 170:
 I turn first to the issue of informer privilege. It was submitted that the law is not clear on this point. The leading cases analyze informer privilege on the basis that some promise of confidentiality express or implied is necessary. However, in R. v. Barros, 2011 SCC 51,  3 S.C.R. 368, Binnie J. seems to have left open the question when he stated, at para. 32: “[i]t might be argued that in a situation of serious potential danger, the informer privilege (or other public interest privilege) might apply even in the absence of the contract-type elements of offer and acceptance.”
 In my view, this matter was settled in R. v. Named Person B, 2013 SCC 9,  1 S.C.R. 405, at para. 18, when Abella J. confirmed that there must be some conduct on the part of the police from which a promise of confidentiality could be inferred, either expressly or implicitly:
The legal question is whether, objectively, an implicit promise of confidentiality can be inferred from the circumstances. In other words, would the police conduct have led a person in the shoes of the potential informer to believe, on reasonable grounds, that his or her identity would be protected?
 In this case there was no conduct on the part of the police, express or implied, that could have led the author to believe that his or her identity would be protected. The police merely received an unsolicited anonymous email. The test for informer privilege is not satisfied on the facts of this case. (This is unlike a “crime stoppers” communication which is founded on a promise of anonymity.)
 I similarly conclude that public interest privilege does not apply. Public interest privilege involves a claim by a government or an official that certain information should be kept secret. Typical situations involve the need to keep police investigative techniques confidential or the protection and safety of individuals. The Crown has the burden of establishing the need to keep the identity of the author secret. The Crown attempted to satisfy this burden by alleging that the author’s mental health issues, fear of police and fear of retribution engage public interest privilege. However, there is no objective evidence underlying the author’s fears. On the record before us, the Crown’s burden has not been met.