How does the law of defamation in Canada work?

As stated in The Law of Defamation in Canada, vol. 3, at pp. 25-149 to 25-152: Damages for defamation may be reduced by evidence that the plaintiff already had a bad reputation. It is true that it is the reputation that the plaintiff has, not the one that he wishes he had, which the law will protect. Damages may be reduced if it is shown that the plaintiff already has a bad reputation. Therefore, a defendant may introduce evidence of the plaintiff’s general bad reputation in the community both before and at the time of the publication, relevant to the defamatory remark. . . . . . Evidence of particular acts of misconduct are not admissible in mitigation of damages, unless they are relevant to proof in support of a plea of justification, or they are “directly relevant to the context in which a defamatory publication came to be made”. [Per May L.J. in Burstein v. Times Newspapers Ltd., [2001] 1 W.L.R. 579 at 596 (C.A.)]