Can You Challenge a Will Before the Person Dies in Ontario?

You've just learned that an elderly parent quietly changed their will, and the new version favours a sibling, a caregiver, or a new partner in a way that feels wrong — or worse, feels like someone is taking advantage of them. Your instinct is to fight it now, before things get worse. Understandably, you want to know whether you can challenge a will before the person dies in Ontario.

The short answer is generally no — at least not directly, and not in the way most people imagine. A will only takes legal effect once its maker (the testator) dies. While they're alive, there's technically nothing yet to challenge. That doesn't mean you're powerless, though. It means the tools available to you look different from a court fight over a finished estate.

This article explains why Ontario law works this way, and what realistic options exist if you're worried about a loved one's capacity or the people around them.

Why a Will Can't Be Contested While the Testator Is Alive

Courts describe a will as "ambulatory" — a term that simply means it has no fixed, final effect until death. Right up until that moment, the person who made it can revise it, revoke it, or tear it up entirely, as many times as they like, provided they still have the legal capacity to do so.

Because of this, a court challenge to a will's validity — on grounds like lack of capacity, undue influence, or improper signing — is really a challenge to something that governs nothing yet. There's no gift to undo, no estate to redirect, and no beneficiary with a legal interest to protect, because the will could be different tomorrow. Ontario courts generally won't hear that kind of challenge in advance.

What You Generally Can't Do

• Ask a court to declare a living person's will invalid
• Ask a court to "lock in" an earlier, more favourable version of the will
• Force disclosure of the will's contents from the testator or their lawyer while the testator is alive and capable — a competent adult's will is private, and they're entitled to keep it that way, even from close family

What You Can Do Instead

If you're genuinely worried about a family member's capacity, or about someone's influence over them, a handful of options exist — though none of them directly attacks the will itself.

1. Raise it directly, respectfully, and calmly. A conversation, sometimes involving a trusted third party, resolves more of these situations than people expect.
2. Encourage independent legal advice. A lawyer meeting privately with the testator, away from the person alleged to be exerting influence, is one of the strongest safeguards against both incapacity and undue influence — and it creates a contemporaneous record if the will is ever challenged later.
3. Consider whether a capacity assessment is appropriate. If there's a genuine, documented concern about mental capacity — not just disagreement with their choices — a qualified capacity assessment can help clarify the picture without anyone needing to be sued.
4. Look at whether guardianship is needed. If a person is already mentally incapable and has no valid Power of Attorney in place, a court-appointed guardian of property or of the person may become necessary to manage their affairs — a more involved process than acting under an existing power of attorney, and generally a separate question from the will itself.
5. Watch for misuse of an existing Power of Attorney. If someone is already acting as attorney and appears to be misusing that authority, that's a live, present-day problem you may be able to address now, unlike a future will.
6. Keep records. Dates, observations, and copies of anything relevant. If a challenge does eventually become necessary after death, this kind of documentation is often what makes or breaks a case.

After Death: A Different Legal World

Once the testator dies, the picture changes completely. The will becomes a live legal document, and a person with a genuine interest in the estate can challenge it on limited grounds — lack of testamentary capacity, lack of knowledge and approval of its contents, undue influence, fraud, or a failure to meet the formal signing requirements. Simply disagreeing with how the estate was divided is not, on its own, one of those grounds.

If you're in the "before death" stage of this problem, the most useful thing you can often do is build the record now, through independent legal advice for the testator, careful documentation, and addressing any live misuse of authority, so that if a real dispute becomes necessary later, it starts from a position of clarity rather than speculation.

Frequently asked questions