Testamentary capacity: what families and lawyers need to know

Testamentary capacity is the mental ability a person needs to make a valid will. When someone has dementia, a brain injury or a serious illness, families and lawyers often worry about whether a new will could later be challenged.

This guide is for lawyers and for families. It explains the common law test, the signs that suggest an assessment is wise, what a clinician looks at, and how evidence is used when a will is disputed after death.

The legal test for testamentary capacity

Across Australia, courts still use the test set out in the English case Banks v Goodfellow (1870). The Australian Law Reform Commission summarises it in four parts. The person making the will (the testator) must:

1. understand the nature of making a will and its effects
2. understand, in general terms, the extent of the property they are giving away
3. be able to comprehend and appreciate the claims of people who might expect to benefit
4. not have a disorder of the mind that poisons their affections, distorts their sense of right, or causes delusions that influence the will.

The test does not require perfect memory or detailed knowledge of every asset. It asks whether the person has a sound enough grasp of what they are doing, what they own and who might have a claim on them.

Capacity is judged at the time the will is made. In a 2023 paper, Justice Lindsay of the NSW Supreme Court noted it may also be relevant at the time instructions were given. The formal rules for making a will sit in state laws, such as the Wills Act 1997 (Vic) and the Succession Act 2006 (NSW).

Common misunderstandings

• A diagnosis does not decide the question. Many people with early dementia still meet the test.
• A single screening score is not enough. A brief memory test can flag concerns, but it does not measure the specific abilities the law asks about.
• An unusual will is not proof of incapacity. People can leave their property as they wish. A large, unexplained change is simply a reason to look more closely.
• Capacity can fluctuate. The law has long accepted that a will signed during a lucid interval can be valid, even where the person’s condition varies.

Capacity is different from undue influence

A will can be challenged for more than one reason. Lack of capacity is about the person’s mental ability. Undue influence is about pressure from someone else.

The ALRC explains that, in probate law, only actual coercion invalidates a will. Persuasion or influence alone is not enough. A person with full capacity can still be coerced, and a person with reduced capacity may be more vulnerable to pressure. A clinician can comment on vulnerability, but whether undue influence occurred is a legal question.

When a capacity assessment is worth considering

Most people making a will do not need a clinical assessment. An assessment may be wise when:

• the person has dementia, mild cognitive impairment, a recent stroke, a brain injury or a serious mental illness
• the person is very unwell, in hospital or near the end of life
• there has been recent delirium, heavy medication use or alcohol misuse
• the new will is very different from earlier wills
• a new beneficiary is closely involved in the person’s care or finances
• there is family conflict, or a challenge seems likely.

An assessment done close to the time of signing gives much stronger evidence than a reconstruction years later. It also gives the person a fair chance to show what they understand.

What a clinician looks at

A neuropsychologist or other suitably trained clinician will usually:

• interview the person alone about the will, their assets, their family and the reasons for their choices
• ask about changes from earlier wills and whether the reasons fit the person’s long-held values
• test memory, attention, language, reasoning and planning
• look for mood problems, psychotic symptoms or delusions that could affect the will
• review medical records and, with consent, speak with treating doctors.

Specialised tools exist, but clinical judgement still matters most. A 2024 systematic review by Aravind and colleagues found that structured tools can supplement a clinical assessment. It concluded that the clinical judgement of a medical professional remains the gold standard.

Giving the person a fair assessment

The assessment should give the person every chance to show what they understand. That means seeing them without family present, using hearing aids and glasses, arranging an interpreter if needed and choosing a time of day that suits them. Questions should be open and should not suggest an answer, so the replies reflect the person’s own understanding.

Tips for lawyers making a referral

• State the legal test and ask the clinician to address each limb.
• Provide the draft will, earlier wills and a simple summary of assets.
• List the people who might reasonably expect to benefit.
• Share relevant medical history and any concerns about influence.
• Keep detailed file notes of your own instructions meeting.

Purser and Rosenfeld argue that clear referral letters reduce confusion between legal and medical professionals.

Retrospective assessments after a death

When a will is challenged after death, a neuropsychologist may be asked for a retrospective opinion. This means reviewing medical records, earlier cognitive tests, care notes, the lawyer’s file and witness statements. The clinician then gives a view about the person’s likely abilities when the will was made.

These opinions have limits, because the person cannot be examined. Justice Lindsay has noted that medical evidence may be critical but may not be decisive in contested cases. Courts weigh it with all the other evidence, including what the lawyer and witnesses saw.

A careful clinician will also say when the records are too thin to support a firm opinion. Gaps in the records are common, particularly for people who saw doctors rarely.

If a person no longer has testamentary capacity

If a person has lost testamentary capacity, their existing will usually stays in place. In Victoria, the Supreme Court can authorise a statutory will under the Wills Act 1997. The Victorian Law Reform Commission explains that the Court must be satisfied that:

• the person lacks testamentary capacity
• the proposed will reflects what the person’s intentions are likely to be
• it is reasonable to authorise the will.

An application usually needs evidence about the person’s current capacity, which a neuropsychological assessment can provide. Other states and territories have their own processes, so check the law where the person lives.

Invictus Health कैसे मदद कर सकता है

Our neuropsychologists provide capacity assessments for wills and other legal decisions. For contested estates, we can provide medico-legal assessments, including file reviews. Neuropsychology reports are reviewed by Dr Judy Tang OAM.

We have clinics in every state and territory. See our fees या संपर्क करें to discuss a referral. This article is general information and is not legal advice. Please speak with a qualified professional about your situation.