What is the test for the defence of qualified privilege against defamatory statements?

The defence of qualified privilege is intended to serve “the general interests of society” and “the common convenience and welfare of society” rather than the interests of individuals or a class: Halls v. Mitchell, 1928 CanLII 1 (SCC), [1928] S.C.R. 125 at 147. Duff J., writing for the majority in Halls v. Mitchell, stated at pages 132-133: The defamatory statement is ... only protected when it is fairly warranted by some reasonable occasion or exigency, and when it is fairly made in discharge of some public or private duty, or in the conduct of the defendant’s own affairs in matters in which his interests are concerned. The privilege rests not upon the interests of the persons entitled to invoke it, but upon the general interests of society, and protects only communications “fairly made” in the legitimate defence of a person’s own interests, or plainly made under a sense of duty, such as would be recognized by “people of ordinary intelligence and moral principles".