I commonly receive estate enquiries where the enquirer strongly asserts suspicion that documents found after death such s a wills or a transfer were forged.
I predicted many years ago with the advent of S. 58 and 59 WESA ( the curative provisions of defective wills) allowing court approval of unwitnessed or even unsigned written or computer wills as valid after being satisfied that the document represents the last stated intention of the deceased’s testamentary wishes.
The potential for financial abuse and in particular by “forgery” is enormous as many have not gone to professional will drafters after learning of the relaxed will rules and how you can now just do your own.
Most of the following law is derived from criminal law but it will apply equally to a civil claim alleging forgery.
A trial judge may make their own handwriting comparison. However, courts have conditioned the use of this power on the trial judge issuing a self-instruction on the dangers of exercising it.
In R. v. Megill, 2021 ONCA 253, the court stated:
The Governing Principles
 At common law, proof of handwriting could be made by testimonial or circumstantial evidence. For example, a witness might testify that they saw the act of writing. Or they might give evidence of the circumstances leading up to or pointing back to the act of writing. In a similar way, a qualified witness may testify about the style of the handwriting which requires a comparison between known and the disputed writing: VII Wigmore on Evidence (Chadbourn Rev. 1978), §1991, at pp. 252-57.
 The common law also permitted the trier of fact, without the aid of experts, to compare handwriting samples when a proved or admitted standard used for comparison with the disputed writing was already properly admitted as evidence for other purposes. No document was admissible merely as a standard of comparison with the disputed writing: R. v. Abdi (1997), 1997 CanLII 4448 (ON CA), 116 C.C.C. (3d) 385 (Ont. C.A.), at para. 15, citing VII Wigmore on Evidence (Chadbourn Rev. 1978), §§1992-1994, at pp. 257-64.
 Under s. 8 of the Canada Evidence Act, R.S.C. 1985, c. C-5, handwriting may be proven by comparison, by expert or lay witnesses, of a disputed handwriting with one that has been proved to be genuine and which has been received in evidence for the purpose of comparison: Abdi, at para. 16.
 Section 8 does not oust the common law rule. The section does not preclude a trier of fact from comparing disputed handwriting with admitted or proved handwriting in documents which are properly in evidence and drawing available inferences: Abdi, at paras. 22, 23 and 25.
In R. v. Hunking, 2016 ONSC 1749, the court stated:
F. The Principles Governing Handwriting Comparisons by the Trier of Fact
 In a series of cases the Ontario Court of Appeal has affirmed that a trial judge as trier of fact may make handwriting comparisons between a known or admitted sample of handwriting and another document bearing handwriting, and find that both were written by the accused. However, the court has conditioned the use of this power on the trial judge’s self-instruction on the dangers in exercising it. These cases include R. v. Abdi (1997), 1997 CanLII 4448 (ON CA), 34 O.R. (3d) 499; 1997 CanLII 4448 (Ont. C.A.), R. v. Malvoisin, 2006 Can LII 33304 (Ont.C.A.), and R.v. Flynn, 2010 ONCA 424.
 In Abdi, 1997 CanLII 4448 Justice Robins for the Court stated:
In the appellant’s submission, s.8 of the Canada Evidence Act (“the Act”) requires that evidence with respect to the comparison of handwriting be given by experts or witnesses with particular knowledge of the writings of the accused. To allow the jury to compare handwritten documents without witness testimony as to the validity of the comparison, the appellant argues, is to turn the jurors into witnesses and deprive the accused of the right of cross-examination. As I noted earlier, the handwriting in the red address book is the appellant’s.
Section 8 of the [Canada Evidence] Act provides:
8. Comparison of a disputed writing with any writing proved to the satisfaction of the court to be genuine shall be permitted to be made by witnesses, and such writings, and the evidence of witnesses respecting those writings, may be submitted to the court and jury as proof of the genuineness or otherwise of the writing in dispute.
Under s. 8, handwriting may be proved by comparison, done by expert or lay witnesses, of the disputed writing with a writing that has been proved to be genuine and which has been admitted into evidence for the purpose of comparison. The question is whether or not, in light of this provision, the trier of fact is entitled to compare the disputed handwriting with the admitted or proved handwriting and form an opinion thereon in the absence of any witness testimony as to the genuineness or otherwise of the disputed writing. Put another way, does s. 8 provide the only means for comparison of handwritten documents and thus preclude comparison by the trier of fact without witness evidence? If the trier of fact does not require such assistance, then the question is what caution need be given as to the dangers of engaging in an unaided comparison.
In R. v. Dixon, supra, the Nova Scotia Supreme Court, Appellate Division, held that the statutory provision allowed the comparison to be made by expert or lay witnesses “or without the intervention of any witnesses at all, by the jury themselves, or, in the event of there being no jury, by the court”.
There is, of course, a potential danger in making unassisted comparisons and the judge’s charge should reflect this danger. The jury should be reminded that it has no expert or other evidence relating to the writings and directed as to the care to be exercised in making the comparison. Any difficulties that a comparison may reasonably present in the light of the circumstances of a given case should be brought to the jury’s attention. As well, the jury may require instruction on the quality of the handwriting exemplar, whether it is of sufficient length and clarity for comparison purposes and, depending on the nature of the facts and the charge, on other matters going to the weight that may be placed upon such a comparison. In cases where forgery or the like is alleged, expert evidence may well be essential.