Challenging a Will for Undue Influence or Lack of Capacity in Western Australia

By James Stevens, Director and Solicitor, Go To Court Lawyers. Last reviewed 10 April 2026.

Suspect a Will Was Made Under Pressure or by Someone Who Lacked Mental Capacity in Western Australia?

If you believe a deceased person's will was created under undue influence or when they lacked the mental capacity to understand their decisions, you can challenge that will in the Supreme Court of Western Australia. These claims are completely separate from family provision applications and require specific evidence of coercion, manipulation, or cognitive impairment at the time the will was signed. You have 12 months from the grant of probate to file your claim, making immediate legal action critical to preserve evidence and protect your rights.

Do You Need a Lawyer?

Yes, you absolutely need experienced legal representation for undue influence and lack of capacity claims in Western Australia. These cases require complex medical evidence, witness testimony, and detailed analysis of the deceased's circumstances when they made their will. The Supreme Court of Western Australia demands strict compliance with procedural requirements and evidence rules that inexperienced applicants consistently fail to meet.

Without a lawyer, you risk having your case dismissed on technical grounds before the court even considers your evidence. Our lawyers have successfully challenged wills where family members, carers, or professionals exploited vulnerable people, recovering millions in assets that would otherwise have been distributed according to invalid wills. The cost of legal representation is often recoverable from the estate if you succeed.

The stakes are enormous - you're not just fighting for money, but ensuring the true wishes of your loved one are respected and preventing those who manipulated them from benefiting from their wrongdoing.

What Happens Next - The Process

1. Urgent evidence preservation: Contact all medical professionals, care facilities, and witnesses who observed the deceased around the time they made their will. This evidence deteriorates rapidly as memories fade and records are destroyed.
2. Obtain complete medical records: Request all GP records, specialist reports, hospital admissions, and mental health assessments from at least 2 years before the will was made until the person's death.
3. Secure witness statements: Interview family, friends, carers, and professionals who can testify about the deceased's mental state, unusual behavior, or signs of pressure from beneficiaries.
4. File originating summons: Lodge your claim in the Supreme Court of Western Australia within 12 months of probate being granted, along with supporting affidavits and medical evidence.
5. Serve all parties: Formally notify all beneficiaries under the contested will and any other interested parties of your challenge.
6. Expert medical assessment: Engage psychiatrists or geriatricians to review medical records and provide expert opinions on the deceased's mental capacity.
7. Discovery process: Exchange all relevant documents with other parties, including financial records, correspondence, and care arrangements.
8. Mediation or trial: Most cases settle through court-ordered mediation, but complex disputes may proceed to a full Supreme Court trial lasting several days.

The entire process typically takes 12-24 months, with urgent applications possible if assets are being dissipated or evidence destroyed.

The Law in Western Australia

Will disputes in Western Australia are governed by the Wills Act 1970 (WA) and decided in the Supreme Court under the Supreme Court Act 1935 (WA). The court applies common law principles established in landmark cases like Banks v Goodfellow for testamentary capacity and Allcard v Skinner for undue influence.

Testamentary capacity requires the will-maker to understand: the nature and effect of making a will, the extent of their property, the claims of potential beneficiaries, and how these factors relate to each other. The test is whether they had sufficient mental capacity at the specific moment they gave instructions for or executed their will.

Undue influence means coercion that overpowers the will-maker's independent judgment, going beyond mere persuasion or emotional appeals. The court looks for evidence of domination, isolation, dependency relationships, and suspicious circumstances surrounding the will's preparation.

Claims must be filed within 12 months of probate being granted, with extensions only in exceptional circumstances. The Supreme Court has unlimited jurisdiction over estate disputes and can set aside entire wills or specific provisions found to be invalid.

Costs typically follow the event, meaning unsuccessful challengers pay both sides' legal costs, often exceeding $50,000-$200,000 for defended cases reaching trial.

Mistakes to Avoid

Confusing capacity challenges with family provision claims. Many families waste months pursuing the wrong type of case. If you're unhappy with your inheritance but the will was validly made, you need a family provision claim under the Family Provision Act 1972 (WA), not a capacity challenge. Capacity challenges only succeed when the deceased genuinely couldn't understand their decisions due to dementia, mental illness, or cognitive impairment.

Waiting too long to gather medical evidence. Doctors move practices, hospitals archive records, and care facilities destroy files after just a few years. We've seen strong cases collapse because families delayed obtaining crucial medical records that proved their loved one's declining mental state. GP records showing confusion, medication effects, or psychiatric symptoms are often the foundation of successful capacity challenges.

Assuming suspicious circumstances alone prove undue influence. Courts distinguish between legitimate influence (like discussing family needs) and undue influence that overrides free will. Simply proving someone isolated the deceased, controlled their finances, or rushed the will preparation isn't enough - you must show this coercion actually caused the will provisions you're challenging.

Failing to consider who benefits from the challenge. Even if you prove the will is invalid, assets typically revert to an earlier valid will or intestacy laws, which may not benefit you at all. We've seen families spend $100,000 successfully challenging a will, only to discover the deceased's assets passed to distant relatives under intestacy rules.

Underestimating the emotional toll of contested proceedings. These cases often destroy family relationships permanently and require detailed examination of your loved one's final years. Many families settle for less than they initially demanded once they understand the personal cost of prolonged litigation.

Likely Outcomes and Costs

Successfully proving undue influence or lack of capacity typically results in the contested will being set aside completely or in part. Assets then distribute according to an earlier valid will, or under intestacy laws if no previous will exists. Courts rarely remake wills based on what they think the deceased "would have wanted" - they either validate or invalidate the disputed document.

With experienced legal representation, strong medical evidence, and clear witness testimony, success rates exceed 60% for genuine capacity challenges. Undue influence claims are more difficult, succeeding in approximately 40% of cases that proceed to trial, as proving coercion requires compelling evidence of manipulation and dependency.

Legal costs for defended capacity and undue influence claims range from $35,000-$75,000 for straightforward cases settling at mediation, up to $150,000-$300,000 for complex matters proceeding to Supreme Court trial. These costs are often recoverable from the estate if you succeed, and may be covered by litigation funding or after-the-event insurance.

Most cases settle within 12-18 months through court-ordered mediation, avoiding the uncertainty and additional costs of trial. Settlements typically involve compromise, with successful challengers receiving more than under the disputed will but less than complete victory.

Going without legal representation virtually guarantees failure - courts dismiss over 90% of self-represented capacity challenges on procedural grounds before considering the merits. The Supreme Court's complex evidence rules and strict deadlines require professional navigation.

How Go To Court Lawyers Can Help

Go To Court Lawyers' estate litigation specialists have successfully challenged hundreds of wills across Western Australia, recovering millions in assets for families whose loved ones were exploited or lacked capacity. Our Perth team includes lawyers who regularly appear in the Supreme Court of Western Australia and understand exactly what evidence judges require for capacity and undue influence claims.

We immediately secure all medical records, interview key witnesses, and engage leading psychiatrists and geriatricians to assess your loved one's mental state. Our systematic approach has achieved successful outcomes even in cases other lawyers considered unwinnable, including challenges to wills made by people with early-stage dementia or under pressure from controlling carers.

With 800+ lawyers nationally and a 4.5-star rating from 780 reviews, we handle estate disputes in every state and territory. Our fixed-fee consultation provides honest assessment of your case's prospects and estimated costs, with no obligation to proceed.

Time is critical in will disputes - evidence disappears, witnesses' memories fade, and strict court deadlines approach rapidly. Call our 24/7 hotline on 1300 636 846 or book your urgent consultation online at gotocourt.com.au/book to protect your rights and ensure your loved one's true wishes are honored.