Summary
Doubt that a will reflects what your parent, spouse or relative wanted? In Ontario, a will can be challenged on several grounds: it wasn’t signed and witnessed properly, the person lacked testamentary capacity, they didn’t know and approve its contents, or someone overbore their wishes through undue influence or fraud. Each ground carries its own burden of proof, and a notice of objection can stop a certificate of appointment from issuing.
For the basics of what makes a will valid, see our guide to the common obstacles to a valid will.
Start with the paperwork: execution and witnesses
Under s. 4(2) of the Succession Law Reform Act, a will isn’t valid unless the testator (or someone signing in their presence and at their direction) signs it at its end, the testator makes or acknowledges the signature before two or more attesting witnesses present at the same time, and at least two of them subscribe the will in the testator’s presence. That rule is subject to the Act’s exceptions, including holograph wills and wills made by members of the forces (ss. 5 and 6), and witnessing by audio-visual communication technology when at least one witness is a licensee of the Law Society of Ontario and the other conditions in s. 4(3) are met.
Two other provisions often come up:
Witnesses who are also beneficiaries. A gift to a person who attests the will, or to their then spouse, is void as to them and anyone claiming under them (s. 12(1)). The Superior Court of Justice can let it stand if satisfied that neither exercised any improper or undue influence on the testator (s. 12(3)), and the gift is not void if the will is attested by at least two other witnesses who have no such interest (s. 12(4)).
Documents that fall short. For deaths on or after January 1, 2022, the Superior Court of Justice can, on application, order an improperly executed document valid as a will if satisfied that it sets out the deceased’s testamentary intentions (s. 21.1(1), (3)). The power is subject to s. 31 of the Electronic Commerce Act, 2000 (s. 21.1(2)).
If you’re putting a will in place and want it signed and witnessed correctly, our wills lawyers in Ottawa can prepare it.
Who has to prove what
In Vout v. Hay, the Supreme Court of Canada set out the allocation. The person putting the will forward (the “propounder”) carries the legal burden on three issues: due execution, knowledge and approval of the contents, and testamentary capacity (para. 26). A rebuttable presumption helps them: once they prove the will was duly executed with the required formalities, after being read over to or by a testator who appeared to understand it, the court will generally presume the testator knew and approved the contents and had capacity (para. 26).
The person attacking the will carries the legal burden on undue influence and fraud (paras. 21, 28). All of this is decided on the ordinary civil standard, a balance of probabilities (para. 24).
Capacity
Testamentary capacity requires the propounder to establish that the testator had a “disposing mind and memory” (Vout v. Hay, para. 20). Evidence that calls capacity into question brings us to suspicious circumstances, below.
Undue influence
Undue influence requires proof that the testator’s assent to the will was obtained by influence such that, instead of representing what the testator wanted, the will is a product of coercion (Vout v. Hay, para. 21). The Court adds a point that matters in practice: a person may well appreciate what they are doing but be doing it as a result of coercion or fraud (para. 29).
Suspicious circumstances
The Court identifies three kinds of suspicious circumstances: those surrounding the preparation of the will, those that call the testator’s capacity into question, and those suggesting the testator’s will was overborne by coercion or fraud (para. 25). When they are present, the presumption is spent and the propounder takes back the legal burden of proving knowledge and approval, and capacity too if the circumstances relate to mental capacity (para. 27). The challenger need only point to some evidence which, if accepted, would tend to negate knowledge and approval or capacity (para. 27). The court scrutinizes the evidence in proportion to the gravity of the suspicion (para. 24). Suspicion of undue influence or fraud doesn’t shift the burden on those issues (para. 28).
How a challenge moves through the court
Notice of objection. Before a certificate of appointment of estate trustee issues, a person who appears to have a financial interest in the estate can file a notice of objection (Form 75.1) (r. 75.03(1)). Unless the court orders otherwise, probate or administration shall not be granted while it is in effect (Estates Act s. 16(b)). It expires three years after filing unless withdrawn or removed sooner (r. 75.03(2)).
Deadlines after the notice. The applicant must serve a notice to objector (r. 75.03(4)). If the objector doesn’t serve and file a notice of appearance within 20 days after service of the notice to objector, the application proceeds as if no objection had been filed (r. 75.03(5)). If the applicant doesn’t move for directions within 30 days after service of the notice of appearance, the objector may (r. 75.03(6)).
After a certificate has issued. Someone with a financial interest can apply to revoke it where it was issued in error or by fraud on the court, or for any other reason the court is satisfied justifies it (r. 75.04). The court can also order the certificate returned so the will’s validity can be determined (r. 75.05(1)(a)).
Directions. A person with a financial interest can apply for directions on procedure (r. 75.06(1)). The court can set the issues, name the parties, direct a statement of claim, and appoint an estate trustee during litigation (r. 75.06(3)). While an action over validity is pending, the court may appoint an administrator, who can’t distribute the residue (Estates Act s. 28). Where the validity of a will is disputed, anyone with an interest in the property affected may be summoned to see the proceeding and, subject to the rules and the court’s discretion, may be permitted to become a party (Estates Act s. 23).
Mediation in Ottawa. Mandatory mediation (Rule 75.1) applies to proceedings commenced in the City of Ottawa on or after January 1, 2001 under rules 75.01, 75.03, 75.05 and 75.08, among others (r. 75.1.02(1)). The court can exempt a proceeding (r. 75.1.04).
Challenging the will isn’t the only route: a dependant who was left without adequate provision can ask the court for support from the estate.
Practical takeaways
If you think a will is invalid:
If no certificate has issued, consider a notice of objection. It holds up the grant while it is in effect (Estates Act s. 16(b); r. 75.03(1)).
Separate your grounds: they carry different burdens (Vout v. Hay, paras. 26–28).
If you’re defending a will or administering the estate:
Keep the execution record. Proof that the will was duly executed and read over to a testator who appeared to understand it supports the presumption (Vout v. Hay, para. 26).
Expect a notice of objection to hold up the grant until it expires, is withdrawn or is removed (r. 75.03(2); Estates Act s. 16(b)).
FAQ
What are the grounds for challenging a will in Ontario?
Improper execution (SLRA s. 4(2)), lack of testamentary capacity, lack of knowledge and approval, and undue influence or fraud (Vout v. Hay, paras. 19–21).
Who has to prove a will is valid?
The person putting it forward must prove due execution, knowledge and approval, and capacity, helped by a presumption (Vout v. Hay, para. 26). Those attacking the will must prove undue influence and fraud (para. 28).
What is undue influence?
Influence that causes the testator’s assent to the will to be a product of coercion rather than what the testator wanted (Vout v. Hay, para. 21).
Can I stop a certificate of appointment from being issued?
Someone with a financial interest can file a notice of objection before it issues (r. 75.03(1)). While it is in effect, the grant shall not be made unless the court orders otherwise (Estates Act s. 16(b)).
Does a will challenge go to mediation in Ottawa?
Generally, yes. Rule 75.1 (mandatory mediation) applies to proceedings commenced in the City of Ottawa under rules 75.01, 75.03, 75.05 and 75.08, among others. The court can exempt a proceeding (r. 75.1.02(1), 75.1.04).
Talk to us
Questioning a will, or defending one as an estate trustee? Our lawyers handle estate litigation for families and estate trustees across Ottawa. Book a consultation: (613) 226-1011 (Mon–Fri, 9 AM–5 PM).
This content is general information about Ontario law as of October 2026. It is not legal advice and does not create a lawyer-client relationship. Laws change and every situation is different. Speak with a lawyer about your specific circumstances. Published October 26, 2026. Written by the lawyers of Francis Mehr LLP (Francis Lawyers), Ottawa.
