- When a will is put forward for probate — formally, an application for a Certificate of Appointment of Estate Trustee — the person propounding it (typically the named estate trustee)…
- Once someone challenges the will, the analysis becomes specific to the ground raised.
- Will challenges are civil proceedings, not criminal ones.
When someone contests a will in Ontario, one of the first questions a lawyer asks is: who has to prove what, and when? The burden of proof in a will challenge does not stay in one place for the whole case — it can start with the person defending the will and shift toward the person attacking it, depending on the ground raised.
Understanding where the burden sits matters because it shapes strategy from the first meeting with a lawyer. It affects what evidence you gather, how the case is argued, and, often, whether pursuing it is worth the cost at all.
This article explains the general framework Ontario courts use, in plain language.
Who Starts With the Burden of Proof
When a will is put forward for probate — formally, an application for a Certificate of Appointment of Estate Trustee — the person propounding it (typically the named estate trustee) generally carries the initial burden of proving three things, on a balance of probabilities:
- The will was properly signed and witnessed, in line with the formal requirements in Ontario's Succession Law Reform Act.
- The testator had testamentary capacity at the relevant time.
- The testator had knowledge and approval of the contents of the document they signed.
Where a will appears valid on its face — properly signed, properly witnessed — courts will usually presume these elements are met without requiring the propounder to prove each one from scratch.
When the Burden Shifts
Once someone challenges the will, the analysis becomes specific to the ground raised.
| Ground for challenge | Who generally carries the burden | What must be shown |
|---|---|---|
| Invalid execution (signing/witnessing) | Propounder (person defending the will) | That the formalities were properly followed |
| Lack of testamentary capacity | Propounder, especially once evidence raises a genuine question | The testator understood the nature of making a will, the extent of their property, and who might reasonably expect to benefit |
| Lack of knowledge and approval | Propounder, once suspicious circumstances are shown | The testator actually knew and approved the document's contents |
| Undue influence | Person challenging the will | That influence overpowered the testator's own free will |
| Fraud or forgery | Person challenging the will | That the document (or a provision in it) is fraudulent or not genuinely the testator's |
The key concept is suspicious circumstances. If the challenger can point to genuinely suspicious facts — for example, the will was prepared by, or heavily benefits, someone closely involved in giving instructions to the lawyer, or it departs sharply from a long-standing prior estate plan — the burden of proving capacity or knowledge and approval can shift back onto the propounder, even though it started there.
The Standard of Proof: Balance of Probabilities
Will challenges are civil proceedings, not criminal ones. Throughout, the applicable standard is the balance of probabilities — is it more likely than not that a fact is true — rather than the much higher criminal standard of proof beyond a reasonable doubt. This applies whether the issue is capacity, knowledge and approval, undue influence, or fraud.
What This Means in Practice
- If you are defending a will, be ready to produce the drafting file, evidence about the testator's condition at signing, and the witnesses' recollection of the signing itself.
- If you are challenging a will, especially on undue influence or fraud, you need more than suspicion — courts expect concrete evidence, not just a sense that something felt wrong.
- Medical records, the drafting lawyer's notes, and witness evidence are usually central to both sides of a capacity or knowledge-and-approval dispute.
Because these matters are fact-driven and the burden can shift mid-case, getting legal advice early — before key evidence disappears or memories fade — makes a real difference.
Frequently asked questions
Does the executor always have to prove the will is valid from scratch?
Not always. If a will looks properly signed and witnessed and nothing raises a red flag, courts generally presume it is valid. The executor's burden becomes active again once a genuine challenge, or suspicious circumstances, are put before the court.
What counts as "suspicious circumstances"?
There is no fixed checklist. Courts look at things like who was involved in preparing the will, whether it departs significantly from earlier wills, and whether the testator's circumstances raise a legitimate question about capacity or influence. Each case turns on its own facts.
Is it harder to prove undue influence than lack of capacity?
Generally, yes. Undue influence requires showing another person's influence actually overpowered the testator's free will — a close relationship or mere opportunity is not enough on its own. Capacity and knowledge-and-approval challenges can sometimes succeed with a lower evidentiary bar once suspicious circumstances are shown.
Who pays if the burden shifts and the challenge still fails?
Cost outcomes in estate litigation are decided separately from who carried the burden of proof, and depend on the circumstances of the case, including how the litigation was conducted. Speak with a lawyer about the cost risk before starting or defending a challenge.
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