What is the current state of the law on requiring an affidavit from the author of a letter?

The Ontario Court of Appeal in the case of Katz v. Katz[14] affirmed this same approach and concern and stated as follows: Before making an order that efficacy of which will depend on the truth of the contents of a letter, a court should at a minimum, require an affidavit from the author of the letter attesting to its contents.

I also adopt the comments of Justice Price in the case of Ceho v. Ceho[15] as follows: Where an unsworn letter or report is tendered for the truth of its contents in respect of contested facts, the closer those facts come to the dispositive issue, the closer scrutiny the letter or report deserves, including submitting to meaningful cross-examination evidence from witnesses with first-hand knowledge of the facts.