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Suspicious Circumstances and Will Validity in Ontario

See how suspicious circumstances can shift the burden of proof to the person defending a will in Ontario, and why undue influence is treated differently.

Wills & Estates4 min readTSLBy the Treadstone Law Team · OntarioUpdated November 1, 2026
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Key takeaways
  • The person defending a will has the legal burden of proving due execution, knowledge and approval, and testamentary capacity.
  • Evidence of suspicious circumstances sends the legal burden back to the person defending the will, but this does not apply to undue influence.
  • A challenger must first point to some evidence that would call the will's validity into question, which is a minimal threshold.

You think something was wrong with how a relative's will came about, perhaps because of who helped arrange it or the person's health at the time. You have heard that suspicious circumstances can shift the burden of proof, and you want to know what that really means.

This article explains who has to prove what in an Ontario will challenge, how suspicious circumstances change that, why undue influence is the exception, and what the first steps in a dispute look like.

Who has to prove what

The person putting forward the will, often the named estate trustee, has the legal burden of proving three things: due execution, knowledge and approval, and testamentary capacity. Due execution means the will was properly signed and witnessed. Knowledge and approval means the person knew what the will said and approved it.

Capacity requires a sound disposing mind. The person must understand the nature and effect of the will, recollect the nature and extent of their property, understand what they are giving, remember the people they might be expected to benefit, and, where it applies, understand the claims of those being excluded.

How the presumption works

Once due execution is proved, the law presumes knowledge, approval and capacity. That presumption can be rebutted, and it puts an evidential burden on the challengers.

If the challengers introduce evidence of suspicious circumstances, the legal burden goes back to the person defending the will. In plain terms, the defender then has to prove again that the will reflects a capable person's real wishes. What counts as suspicious depends on the facts of each case, and a lawyer can tell you whether what you have seen is likely to qualify.

Undue influence is treated differently

Many people assume suspicious circumstances help with every kind of challenge. They do not. The burden of proving undue influence stays on the people attacking the will, and suspicious circumstances do not shift it.

Testamentary undue influence means outright and overpowering coercion of the person making the will, and it must be proved on a balance of probabilities. A presumption of undue influence applies only to lifetime transactions, not to wills, so a challenger to a will gets no presumption and must prove coercion.

IssueWho carries the burden if suspicious circumstances are shown
Due executionThe person defending the will
Knowledge and approvalThe person defending the will
Testamentary capacityThe person defending the will
Undue influenceThe people attacking the will

Getting the challenge in front of the court

Before the court will require a will to be formally proved, the challenger must adduce or point to some evidence that, if accepted, would call the will's validity into question. That is a minimal evidentiary threshold.

Before a certificate of appointment of estate trustee is issued, a person who appears to have a financial interest can file a Notice of Objection (Form 75.1) stating the nature of their interest and of the objection. If the Registrar tells the probate applicant, the applicant must send a notice to the objector (Form 75.3) and file a copy with an affidavit of service. A person with a financial interest can also file Form 74P to be notified when someone starts a proceeding involving the estate.

In the Toronto Region, the Estates List of the Superior Court of Justice hears estate, trust and capacity matters, and the court has considerable discretion and flexibility to set a process for a contested estate. Mandatory mediation applies to certain estates proceedings unless the court grants an exemption. Whether it applies to you depends on where the case is heard and what kind of proceeding it is.

What to do next

Frequently asked questions

What are suspicious circumstances?

They are facts that raise real doubt about whether the will reflects the wishes of a capable person who knew and approved its contents. Which facts qualify depends on the case. If challengers introduce such evidence, the legal burden goes back to the person defending the will.

Does the burden shift if I allege undue influence?

No. The burden of proving undue influence stays on the people attacking the will, and suspicious circumstances do not shift it. You must prove overpowering coercion on a balance of probabilities.

Do I get a presumption of undue influence against a will?

No. That presumption applies only to lifetime transactions, not to wills. A challenger to a will must prove coercion.

How much evidence do I need to start?

Before the court will require a will to be formally proved, you must point to some evidence that, if accepted, would call its validity into question, which is a minimal threshold. A lawyer can help judge whether your evidence meets it.

Sources

Links go to official government, court and regulator pages. The law changes — confirm you are reading the current version.

This article is general information, not legal advice. Reading it does not create a lawyer-client relationship. Ontario laws, tax rates, and government programs change, and how the law applies depends on your specific facts. For advice about your situation, speak with a licensed Ontario lawyer. Treadstone Law is licensed by the Law Society of Ontario — reach us at 1-844-900-1070 or start a file online.

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