In casual conversations the duty of confidentiality and the protection of solicitor-client privilege may be lumped together, as both operate to protect client information from disclosure. However, their roots in law and the exceptions that apply to each concept are different. Knowing the source of the obligations will avoid ethical missteps.
Your ethical duty of confidentiality extends to all the information you learn working for your client. This duty exists no matter the source of the information or its confidential status before it became part of the solicitor-client relationship.
The basis for this ethical duty is, in Quebec, the Code of Ethics of Advocates and other legislation and, in the other provinces and territories, the law society codes of conduct. The codes also describe the exceptions to the ethical duty of confidentiality; they differ in some jurisdictions.
Your duty of confidentiality also exists in common law, stemming from the relationship between lawyer and client. The common law has not developed clear exceptions to this duty.
In contrast, solicitor-client privilege only applies to communications between you and your client for the purpose of legal advice. The privilege is rooted in the common law.
In 2010, the Supreme Court of Canada stated, in the Canadian Criminal Lawyers’ Association case concerning the Charter and access to information, that “the only exceptions recognized to the [solicitor-client] privilege are the narrowly guarded public safety and right to make full answer and defence exceptions.”
With respect to both the duty of confidentiality and solicitor-client privilege, clients may consent to the disclosure of information. In certain circumstances, they may be found to have waived confidentiality or solicitor-client privilege.