When it comes to will challenges, claims must be backed by evidence. The decision of the Ontario Superior Court of Justice in Mitten (Peterson) v Peterson, 2025 ONSC 6082, reinforces this point while offering practical guidance for self-represented litigants.
Background
David passed away on October 17, 2024, leaving a very modest estate. The Applicant, Patricia (representing herself) was David’s separated spouse, and the Respondent, Linda, was his mother.
David first executed a Will in June of 2022 naming Patricia as sole beneficiary. After marrying Patricia in September of 2022, the couple separated in early 2023. Following the separation, David signed a new Will on October 24, 2023 (the “2023 Will”) appointing Linda as both Estate Trustee and sole beneficiary. Evidence indicates David reviewed and provided detailed instructions for the 2023 Will prior to its execution.
The Challenge
Patricia challenged the validity of the 2023 Will, claiming David lacked testamentary capacity when it was executed. Patricia relied on a Manulife Financial Group Benefits Attending Physician’s Update (the “Manulife Document”) dated January 18, 2023, which noted David’s serious health conditions. Patricia also alleged that David suffered from Wernicke-Korsakoff syndrome (“WKS”), though the evidence provided did not support this diagnosis. Additionally, she cited a Certificate of Incapacity (the “Certificate”) from October 2023 related to David’s CPP benefits, but notably, the Certificate did not state that David was incapable of managing his legal affairs.
Courts Decision – Due Execution
The court upheld the validity of the 2023 Will. At the outset, the burden rested on the Respondent to establish due execution, knowledge and approval, and testamentary capacity. Citing Issa v Aiello, 2025 ONSC, the court reiterated:
“Once the preconditions of due execution have been met, the propounder of the Will benefits from a presumption that the testator knew and approved of the contents of the Will and had testamentary capacity…”
The court had no difficulty finding that the 2023 Will was duly executed. David retained independent legal counsel, reviewed drafts, and signed the Will in the presence of witnesses.
The Applicant’s Evidence
Given the finding of due execution, the burden shifted to Patricia to produce “some evidence” capable of rebutting the presumption of knowledge, approval, or capacity. Patricia’s primary argument was that David suffered from WKS. However, the court noted that even if WKS were established, it would not automatically negate testamentary capacity.
At paragraph 46, the court underscored the following point:
“Considering the quality of the Applicant’s evidence, which includes frequent inconsistencies, multiple misinterpretations or misstatements regarding Mr. Peterson’s medical records, and refusals to respond to relevant questions, I conclude that relying on Ms. Mitten’s highly subjective interpretation of events would be risky without confirmatory evidence. There is no affidavit evidence from Dr. Evans, Mr. Peterson’s physician, or from any other independent source. As a result, the existence of medical documentation assumes greater importance in establishing whether the Applicant has succeeded in pointing to ‘some evidence’ that, if accepted, would tend to negative knowledge and approval, or testamentary capacity.”
Furthermore, the court found that neither the Manulife Document nor the Certificate raised suspicious circumstances, as they were not directly related to David’s testamentary capacity in October of 2023. While acknowledging his poor health and history of alcoholism, the court held these factors alone were insufficient to question capacity.
Conclusion
This decision underscores a fundamental principle in estate law: a properly executed will carries a strong presumption of validity. Overcoming that presumption requires clear, contemporaneous evidence, not speculation or unrelated medical records. In today’s landscape, where self-represented litigants are increasingly common in estate disputes, this point is critical.
Thanks for reading!
David Morgan Smith and Emily Adamo (student-at-law)