After deciding that the determination of whether a ‘reasonable expectation of privacy” exists in communications is contextual, have now found that the nature of the relationship is context. Specifically (?) you do not have an expectation of privacy in a sexual communication with someone you believe to be a child, who is a stranger to you.

A man who was convicted of luring a 14-year-old girl over the Internet had no expectation of privacy in his online communications with “Leann,” who in reality was an undercover police officer, the Supreme Court of Canada ruled today, in a judgement in which the judges diverged on approaches to privacy.

Source: No expectation of privacy in child-luring cases on the Internet, SCC rules | Canadian Lawyer Mag