Evidence - Solicitor-Client Privilege
Canada (National Revenue) v. Thompson (SCC, 2016)
In this case the Supreme Court of Canada briefly reviews the nature of solicitor-client privilege:
 Solicitor-client privilege has evolved from being treated as a mere evidentiary rule to being considered a rule of substance and, now, a principle of fundamental justice (Foster Wheeler Power Co. v. Société intermunicipale de gestion et d’élimination des déchets (SIGED) inc., 2004 SCC 18 (CanLII),  1 S.C.R. 456, at para. 34; Lavallee, Rackel & Heintz v. Canada (Attorney General), 2002 SCC 61 (CanLII),  3 S.C.R. 209, at para. 49; Maranda v. Richer, 2003 SCC 67 (CanLII),  3 S.C.R. 193, at para. 11; Solosky v. The Queen, 1979 CanLII 9 (SCC),  1 S.C.R. 821, at p. 839; Descôteaux v. Mierzwinski, 1982 CanLII 22 (SCC),  1 S.C.R. 860, at p. 875; Canada (Attorney General) v. Federation of Law Societies of Canada, 2015 SCC 7 (CanLII),  1 S.C.R. 401, at paras. 8 and 84). The obligation of confidentiality that springs from the right to solicitor-client privilege is necessary for the preservation of a lawyer-client relationship that is based on trust, which in turn is
indispensable to the continued existence and effective operation of Canada’s legal system. It ensures that clients are represented effectively and that the legal information required for that purpose can be communicated in a full and frank manner (R. v. Gruenke, 1991 CanLII 40 (SCC),  3 S.C.R. 263, at p. 289 . . .).  In Descôteaux, one of the earliest cases in which this Court acknowledged that solicitor-client privilege involves a substantive right, Lamer J., as he then was, elaborated on the various aspects of the privilege as follows:
(Foster Wheeler, at para. 34)
1. The confidentiality of communications between solicitor and client may be raised in any circumstances where such communications are likely to be disclosed without the client’s consent.The third and fourth elements of this substantive rule have together been interpreted to support the proposition that an intrusion on solicitor-client privilege must be permitted only if doing so is absolutely necessary to achieve the ends of the enabling legislation (Goodis v. Ontario (Ministry of Correctional Services), 2006 SCC 31 (CanLII),  2 S.C.R. 32, at para. 24).
2. Unless the law provides otherwise, when and to the extent that the legitimate exercise of a right would interfere with another person’s right to have his communications with his lawyer kept confidential, the resulting conflict should be resolved in favour of protecting the confidentiality.
3. When the law gives someone the authority to do something which, in the circumstances of the case, might interfere with that confidentiality, the decision to do so and the choice of means of exercising that authority should be determined with a view to not interfering with it except to the extent absolutely necessary in order to achieve the ends sought by the enabling legislation.
4. Acts providing otherwise in situations under paragraph 2 and enabling legislation referred to in paragraph 3 must be interpreted restrictively. [p. 875]
 Although Descôteaux appears to limit the protection of the privilege to communications between lawyers and their clients, this Court has since rejected a category-based approach to solicitor-client privilege that distinguishes between a fact and a communication for the purpose of establishing what is covered by the privilege (Maranda, at para. 30). While it is true that not everything that happens in a solicitor-client relationship will be a privileged communication, facts connected with that relationship (such as the bills of account at issue in Maranda) must be presumed to be privileged absent evidence to the contrary (Maranda, at paras. 33-34; see also Foster Wheeler, at para. 42). This rule applies regardless of the context in which it is invoked (Foster Wheeler, at para. 34; R. v. Gruenke, 1991 CanLII 40 (SCC),  3 S.C.R. 263, at p. 289).