Constitutional Protection of Solicitor Client Privilege

Canada (Attorney General) v. Chambre des notaires du Québec, 2016 SCC 20:

[35] In our view, therefore, it is well established that a client of a notary or a lawyer has a reasonable expectation of privacy for information and documents that are in the possession of the notary or lawyer and in respect of which a requirement is issued. Indeed, the Court wrote in Lavallee that "[a] client has a reasonable expectation of privacy in all documents in the possession of his or her lawyer, which constitute information that the lawyer is ethically required to keep confidential" (para. 35).
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[38] In Lavallee, the Court stated that "solicitor‑client privilege must remain as close to absolute as possible if it is to retain relevance" (para. 36). In Smith, the Court noted that "[t]he disclosure of the privileged communication should generally be limited as much as possible" (para. 86). This means that any legislative provision that interferes with professional secrecy more than is absolutely necessary will be labelled unreasonable (Lavallee, at para. 36). Absolute necessity is as restrictive a test as may be formulated short of an absolute prohibition in every case (Goodis, at para. 20). In short, "[t]he appropriate test for any document claimed to be subject to solicitor‑client privilege is 'absolute necessity'" (Goodis, at para. 24). Stringent standards must therefore be adopted to protect it. A procedure will withstand Charter scrutiny only if its impact on the professional secrecy of legal advisers is minimal, as minimal impairment "has long been the standard by which this Court has measured the reasonableness of state encroachments on solicitor‑client privilege" (Lavallee, at para. 37).