Mainstream Canada v. Staniford, 2013 BCCA 341 holds:
 In order for the defence of fair comment to succeed, it is necessary for the comment to have a factual foundation or factual substratum. The comment must be an expression of opinion on a known set of facts, and the audience must be in a position to assess or evaluate the comment. The rationale for this requirement was explained over a century ago in the South African case decided by the Transvaal Supreme Court in Roos v. Stent and Pretoria Printing Works, Ltd., 1909 T.S. 988 at 998 per Innes C.J.:
But it is obvious that to entitle any publication to the benefit of this defence it must be clear to those who read it what the facts are and what comments are made upon them. And for two reasons. Because it is impossible to know whether the comments are fair unless we know what the facts are; and because the public must have an opportunity of judging the value of the comments.
 In WIC Radio Ltd. v. Simpson, 2008 SCC 40 (CanLII), 2008 SCC 40,  2 S.C.R. 420, Mr. Justice Binnie agreed with this Court that "a properly disclosed or sufficiently indicated (or so notorious as to be already understood by the audience) factual foundation is an important objective limit to the fair comment defence" (para. 34). He also stated, at para. 31:
What is important is that the facts be sufficiently stated or otherwise be known to the listeners that listeners are able to make up their own minds on the merits of [the] comment.
This passage was also quoted by the trial judge.
 In Channel Seven Adelaide Pty Ltd v. Manock,  HCA 60, the High Court of Australia was called upon to decide for the purposes of the defence of fair comment whether it was sufficient for the "subject matter" of the comment to be notorious or sufficiently indicated. In their joint reasons on behalf of the majority of the Court, Gummow, Hayne and Heydon JJ. held that it was not sufficient, and that it is necessary for the facts on which the comments are based to be "sufficiently indicated or notorious to enable the viewers who saw the promotion to judge for themselves how far the opinions expressed in the 'comments' were well founded" (para. 74).
 In the course of their reasons, the majority of the Court commented on the required linkage between the comment and the supporting facts:
 … a sufficient linkage between the comment alleged and the factual material relied on can appear in three ways: the factual material can be expressly stated in the same publication as that in which the comment appears (ie by "setting it out"); the factual material commented on, while not set out in the material, can be referred to (ie by being identified "by a clear reference"); and the factual material can be "notorious". Those propositions are supported by other authority in Australia, England, South Africa, Hong Kong and the United States.
[Emphasis added; endnotes omitted.]
The phrase "by a clear reference" in the above passage comes from Odgers on Libel and Slander, 6th ed. (1929) at 166, which was quoted with approval in Kemsley v. Foot,  A.C. 345 at 356 (H.L.). I should note that Channel Seven Adelaide was not cited to us at the hearing of this appeal, and I infer that it was also not cited to the trial judge.
 Although the countries listed at the end of para. 49 of Channel Seven Adelaide do not include Canada, it is my view that the statement contained in that paragraph is the law in Canada as well. There is no principled reason why the law in this regard should be different in Canada than the law in the listed common law countries. Channel Seven Adelaide was cited with approval by the Supreme Court of Canada at para. 49 of WIC Radio (albeit on another point), and the statement is consistent with the expression at para. 34 of WIC Radiothat the factual foundation for the comment must be "properly disclosed", "sufficiently indicated" or "notorious".