Grounds for Contesting a Will: The Legal Tests

What Are the Legal Grounds for Contesting a Will?

You cannot contest a will simply because it is unfair — you need a recognized legal ground. In both Canada and the United States, the accepted grounds are: lack of testamentary capacity, undue influence, improper execution, fraud or forgery, revocation by a later will or marriage, and — in Canada and a minority of US contexts — a dependant's relief or family maintenance claim where the will fails to provide for someone the deceased was obliged to support. Disappointment is not a ground; roughly speaking, courts ask whether the will reflects the free, informed intention of a capable testator, not whether it was kind.

Only a small fraction of wills are ever challenged, but the number is rising with blended families, later-life marriages, and the largest intergenerational wealth transfer in history underway — an estimated $1 trillion in Canada and tens of trillions in the US moving between generations this decade. If you are weighing a challenge, our free Contesting a Will wizard screens your facts against the grounds and deadlines below in a few minutes.

Ground 1: Lack of Testamentary Capacity

The testator must have understood, at the moment of signing, four things — the classic test from Banks v Goodfellow (1870), still the law across Canada and the template in most US states: the nature and effect of making a will, the extent of their property, the persons who would ordinarily expect to benefit, and how the will disposes among them, free of a disorder of the mind poisoning those judgments. Capacity is task-specific and time-specific: a person with early dementia can have good days and validly sign; a diagnosis alone proves nothing.

Evidence that wins capacity cases: medical records around the signing date, the drafting lawyer's notes (competent estate lawyers document capacity assessments precisely because of future challenges), retrospective capacity opinions from geriatric specialists, and testimony from people who saw the testator regularly. Red flags that support a challenge include a will made shortly after a dementia diagnosis, radical unexplained departure from a long-standing estate plan, and a new will signed in hospital or in the final weeks of life.

Ground 2: Undue Influence

Undue influence means coercion — pressure that overpowered the testator's free will so that the document expresses the influencer's wishes, not the testator's. Persuasion, flattery, and even nagging are legal; domination is not. Classic fact patterns: a caregiver or new partner who isolates an elderly person from family, controls their communications and appointments, arranges the lawyer, drives them to the signing, and emerges as the main beneficiary of a will that disinherits children without explanation.

The burden usually sits on the challenger, which makes these cases evidence-hungry: phone and visit records showing isolation, financial records showing escalating control, testimony from home-care workers, and the timing of the will relative to the influencer's arrival. Many US states ease the burden with a presumption of undue influence where a person in a confidential relationship actively procured a will that benefits them; several Canadian provinces (including BC under s. 52 of WESA) have similar burden-shifting rules. Suspicious circumstances also strip the will of its usual presumption of validity, forcing the propounder to prove capacity and knowledge-and-approval affirmatively.

Grounds 3 and 4: Execution Defects, Fraud, and Forgery

A will must be executed with statutory formalities: in almost every Canadian province and US state, that means signed by the testator (or at their direction) in the presence of two witnesses present at the same time, who each sign in the testator's presence — and a witness who is also a beneficiary generally voids the gift to that witness, though not the whole will. Holograph wills (entirely handwritten and signed, no witnesses) are valid in most Canadian provinces and about half of US states. Failures happen constantly with DIY and online wills: one witness instead of two, witnesses signing later, unsigned pages, or clauses added after execution.

Modern law softens some of this. Ontario (since 2022), BC, and several other jurisdictions now have substantial-compliance or court-validation powers allowing a judge to uphold a document that clearly expresses testamentary intent despite formal defects — so an execution defect starts, rather than ends, the argument. Fraud and forgery are rarer but absolute grounds: a forged signature (attacked with handwriting experts) or a will signed because of a lie ("your daughter is dead," "this is just a power of attorney") invalidates the instrument.

Ground 5: Dependant Relief — Valid Will, Inadequate Provision

Even a perfectly valid will can be varied. Every Canadian province lets defined dependants — spouses (including common-law in most provinces), minor children, and adult children or others the deceased was supporting — claim support from the estate where the will fails to make adequate provision: dependant's support under Part V of Ontario's Succession Law Reform Act, and, most powerfully, BC's wills variation regime under WESA, which lets even self-sufficient adult children ask the court to rewrite the will on moral-obligation grounds. In the US there is no general equivalent, but a surviving spouse in nearly every separate-property state can take an elective share — typically one-third to one-half of the estate — regardless of what the will says, and community-property states protect the spouse's half of community assets automatically.

This is the ground most families overlook: you do not need to prove anything was wrong with the will, only that the law imposed obligations the will ignored. It is also the main route for the common-law partners and blended-family members that intestacy and outdated wills leave behind — the same people we flagged in What Happens If You Die Without a Will?.

Deadlines: The Clock That Kills More Claims Than Any Defence

Limitation periods in estate litigation are short and unforgiving:

Ontario: dependant support claims must generally be brought within 6 months of the grant of probate; spousal equalization elections under the Family Law Act have the same 6-month window. General validity challenges fall under the 2-year limitation, running from discovery.
British Columbia: a WESA wills variation claim must be started within 180 days of the grant of probate — one of the hardest deadlines in Canadian estate law.
United States: will contests are typically tied to the probate proceeding — as short as 120 days after admission of the will in California, three months to two years elsewhere, and elective-share elections commonly must be filed within 6–9 months of death or probate.

Practical implication: if you suspect a problem, act before probate is granted, not after distribution. Filing a caveat or notice of objection freezes the grant; once the estate is paid out, even a winning claim may chase money that is gone. Contested estates commonly cost $50,000–$250,000+ in fees and take 1–3 years, which is why 80–90% settle at or before mediation (mandatory in Toronto estate cases). Start with the Contesting a Will wizard, use the Inheritance Dispute wizard to map a broader family conflict, read more at the Estate Planning hub, or contact us to be connected with an estate litigator in your jurisdiction before a deadline closes the door.

Frequently Asked Questions

Can I contest a will just because it's unfair?

No. Unfairness alone is not a ground. You need lack of capacity, undue influence, an execution defect, fraud or forgery, or a dependant relief/elective share claim — the exception being BC, where WESA lets even independent adult children seek variation of an unjust will.

What is the deadline to contest a will?

It is short: 180 days from probate for BC wills variation claims, 6 months from probate for Ontario dependant support, as little as 120 days after the will is admitted in California, and 6–9 months for most US spousal elective shares. Missing it usually ends the claim.

What proves lack of testamentary capacity?

Under Banks v Goodfellow, the testator must have understood the will's effect, their property, and their expected beneficiaries. Medical records around the signing date, the drafting lawyer's notes, and retrospective geriatric assessments are the decisive evidence.

What counts as undue influence over a will?

Coercion that overpowers the testator's free will — not mere persuasion. Isolation of an elderly testator, a beneficiary who arranged and attended the signing, and a sudden unexplained disinheritance are the classic indicators, and suspicious circumstances can shift the burden of proof.

Can a common-law partner challenge a will that leaves them nothing?

Yes, in most Canadian provinces, through dependant relief — Ontario's Succession Law Reform Act includes common-law spouses of 3+ years (or with a child). In the US, unmarried partners have no elective share, making these claims far harder.

How much does contesting a will cost?

Contested estate litigation commonly runs $50,000–$250,000+ over 1–3 years, which is why 80–90% of cases settle, often at mediation. Courts no longer routinely pay everyone's costs from the estate — losing challengers can bear their own fees.

What Are the Grounds for Contesting a Will?