Suppose I write in a public Facebook post that Joe the Roofer is a liar and a dishonest person. My post causes Joe to lose customers and his revenue decreases.

Joe sues me for defamation.

Shortly after the litigation is commenced, Joe is the subject of a local scandal involving an adulterous relationship between Joe and a prominent woman in town. The scandal is reported on in the town newspaper and Joe's infidelity becomes publicly known.

In my defense in the context of the defamation lawsuit, can I point to Joe's adultery as evidence that the statements I posted online are true, or am I blocked from doing so because at that time I cannot prove that I knew Joe was an adulterer?

In other words, can I defend against a defamation suit with information that only became available after the alleged act of defamation?

  • 1
    Infidelity is not inherently proof that someone is a liar and a dishonest person. Dishonesty and infidelity are often companions, but they aren't equivalent or synonymous. This is particularly true when by calling someone "Joe the Roofer" it appears that the dishonestly described originally is dishonestly by Joe in connection with his roofing business.
    – ohwilleke
    Commented Apr 1 at 23:13
  • Yes, but if my accusation was that he is a dishonest person, without specifying that it was about his business practices or in his personal life, doesn't the fact that he violates his marital vows prove that I am right? Commented Apr 3 at 18:19
  • @CoitBugstein No. It doesn't. Violating one's marital vows is a breach of a marriage contract but is not inherently dishonest.
    – ohwilleke
    Commented Apr 3 at 18:21

1 Answer 1


I will ignore whether the particular statement in your hypothetical could be defamation (as opposed to opinion), and move on to your substantive question about how to establish the defence of truth.

I will present how the defence of truth works in Canada.

In Canadian defamation law, the plaintiff can make out their defamation claim if they show that a statement by the defendant: (1) was about the plaintiff, (2) was defamatory (in the sense that it would tend to lower the reputation of the plaintiff), and (3) was published (communicated to at least one person other than the plaintiff).

Once those elements are made out, the burden flips to the defendant to establish a defence. One available defence is "justification" or "truth." This requires the defendant to demonstrate that the statement was true at the time it was made. (That is a significant difference compared to U.S. law; in the states, the plaintiff has the onus of demonstrating the falsehood of the defamatory statement.)

Evidence about the truth of the statement at the time it was made can come from before, contemporaneous with, or after the statement was made. But it is not good enough to show that the statement, had it been made at a later time, would have been true at some later time. To succeed in a defence of truth, the defendant needs to show that it was true at the time it was made.

It is also not about what you knew or believed. You can luck into a defence of truth.

See Viex Events Ltd. v. Abela, 1997 CanLII 1512 (BC SC), at para 45:

Truth is a complete defence to defamation and does not require the literal truth of every fact in the publication, just that the statements in their entirety are substantially correct at the time they were made.

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