Yes, and it is the most common ground. The testator must understand the nature of making a will, the extent of their property, and who might expect to benefit.
The Canadian position
Capacity is assessed at the time of signing. Suspicious circumstances can shift the burden onto the person propounding the will.
The Islamic position
Classical fiqh likewise requires soundness of mind for a valid wasiyyah, and treats deathbed dispositions under separate rules.
Where the four schools differ
This question turns on one issue in our madhhab register: Making a wasiyyah — form, capacity and revocation — what does a wasiyyah have to look like, and what must the person making it be, for it to be validly made — and how is it undone?
Researched positions from our madhhab register — issue wasiyyah-formation, reviewed 2026-09-01.
Three things the four schools do not divide on, and they are the three a Canadian family usually needs. First, revocation. The Kuwaiti Mawsu’a records it as agreed — “the jurists agreed that a wasiyyah is a non-binding contract, and that the testator may in his lifetime revoke it in whole or in part”, whether he made it in health or in his last illness — and Ibn Qudama reports the same as ijma‘, naming Malik, al-Shafi‘i and Ahmad. Revocation needs no formality: saying so does it, and so does any act inconsistent with the bequest — selling the thing, giving it away, giving it in charity, making it a dower or a waqf. (Merely using the thing does not. And al-Mughni reports a contrary view from the ‘people of opinion’ that a sale is not a revocation because a substitute came in for it, a view later Hanafi manuals do not follow; the Mawsu’a records the sale rule as agreed.) Second, capacity: sound mind is a condition by express agreement, so the bequest of a madman, of one whose reason has gone and of an unconscious person is void in every school. Third, coercion. The classical category is ikrah, and a wasiyyah made under it is not merely voidable but void — the Mawsu’a puts the coerced, the joking and the mistaken together, “because these accidents destroy consent”, with Hanafi, Maliki and Shafi’i authority; the Hanbali rule that verbal dispositions fall void under coercion is stated in the same encyclopaedia’s entry on ikrah rather than in its section on wills. One recorded Maliki qualification runs the other way on revocation: where the testator declared in the will itself that there was to be no revoking it, the Malikis are reported not to let a revocation undo it.
Full positions, evidence and history: Making a wasiyyah — form, capacity and revocation — the issue page.
Related madhhab issue: A gift made in the final illness — gift or bequest?.
What to do about it
- Make the will while clearly well, not in a crisis.
- Have the lawyer record capacity observations.
- Consider a capacity assessment if there is any history of cognitive difficulty.
This is legal information only. For advice on your own circumstances, speak to a lawyer.
Citations & sources
Every factual claim on this page traces to a source below. Details change — check the original source before relying on any figure, fee or legal position. Anything under “further reading” is related material, not a source for what is stated here.
- Grewal v. Litt, 2019 BCSC 1154 — CanLII
- Wills, Estates and Succession Act, SBC 2009, c 13 — BC Laws
- Canadian Legal Information Institute — CanLII
- Substitute Decisions Act, 1992 — Government of Ontario
- Suspicious circumstances doctrine will challenge ontario — Treadstone Law
- Common mistakes making a will ontario — Treadstone Law
- Capacity to instruct a lawyer ontario — Treadstone Law
- Testator capacity decline updating will ontario — Treadstone Law
- Wills & estates practice — Treadstone Law