Testamentary Capacity & Suspicious Will Changes — When Dementia, Illness or Last-Minute Changes Undermine a Will

The Banks v Goodfellow test (1870)

The test for testamentary capacity was stated by Cockburn CJ in Banks v Goodfellow (1870) LR 5 QB 549 and has been consistently applied by Australian courts for over 150 years. To have testamentary capacity, the will-maker must, at the time of executing the will:

1. Understand the nature of making a will and its effects. The testator must understand that they are disposing of their property on death and comprehend the significance of the document they are signing.
2. Understand the extent of the property they are disposing of. The testator must have a general understanding of what they own — not an exact inventory, but a broad appreciation of the nature and value of their assets.
3. Comprehend and appreciate the claims to which they ought to give effect. The testator must be able to consider the persons who might reasonably expect to benefit from their estate — spouses, children, dependants, and others with a moral claim — and make a rational assessment of those claims.
4. Be free from any disorder of the mind that would poison their affections, pervert their sense of right, or prevent the exercise of their natural faculties. This limb addresses the effect of mental illness, delusions, or cognitive impairment on the testator's decision-making. A delusion that causes the testator to disinherit a child based on a false belief, for example, may vitiate capacity.

Importantly, the test is applied at the time of execution. A person may have fluctuating capacity — lucid one day and confused the next. The question is not whether the testator had capacity generally during the final years of their life, but whether they had capacity on the specific day and at the specific time when they executed the will.

Capacity vs undue influence — understanding the distinction

These two grounds for challenging a will are often confused but are fundamentally different:

It is common — and often prudent — to plead both grounds in the alternative. For example, a will made by an elderly person with dementia who was also isolated and controlled by a new carer may be challenged on the basis that the testator lacked capacity, and alternatively that if the testator had capacity, their free will was overborne by undue influence.

When a will change is suspicious — factors that warrant scrutiny

Not every will made late in life or during illness is invalid. People are entitled to change their minds. However, certain factors, particularly in combination, may raise a suspicion that the will does not reflect the testator's true intentions. These are sometimes referred to as "suspicious circumstances" and may shift the evidentiary burden to the person propounding the will.

• Radical departure from long-standing intentions. A parent who always treated children equally suddenly disinherits all but one — typically the person now controlling access or providing care.
• Timing close to death. The will was executed in the testator's final days or weeks, in hospital, in a nursing home, or during a period of known cognitive decline.
• New and controlling relationship. A new spouse, carer, friend, or advisor — particularly one who appeared late in the testator's life — becomes the primary beneficiary to the exclusion of family.
• Isolation from family and independent advisors. The testator was cut off from children, siblings, long-standing friends, and professional advisors around the time the will was made.
• Beneficiary involved in will preparation. The person who benefits most from the will arranged the solicitor, was present at the conference, gave instructions on the testator's behalf, or communicated with the solicitor independently.
• Multiple wills in quick succession. A series of wills made over a short period, each increasingly favouring the same person, with no rational explanation for the changes.
• Will prepared without independent legal advice. A homemade will, a will kit, or a will prepared by a solicitor who was not independent (e.g., a solicitor who is also a beneficiary).
• Testator's vulnerability. The testator was elderly, unwell, grieving, dependent on others for care, or suffering from a condition known to affect cognition (dementia, stroke, delirium, etc.).

Medical evidence in capacity cases

Medical evidence is often central to capacity challenges. However, the court is not bound by medical opinion — the question of testamentary capacity is ultimately a legal question for the court, informed by but not determined by medical evidence.

The most useful medical evidence includes:

• Contemporaneous medical records — GP notes, hospital records, and specialist reports from the period surrounding the will's execution. These are generally more valuable than retrospective expert reports.
• Cognitive assessments — Mini-Mental State Examination (MMSE) scores, formal neuropsychological testing, or other cognitive evaluations conducted around the relevant time.
• Diagnoses of conditions affecting cognition — dementia (Alzheimer's, vascular dementia, Lewy body dementia), delirium, stroke, traumatic brain injury, psychiatric illness.
• Medication records — particularly medications with cognitive side effects: opiates, benzodiazepines, anticholinergics, and sedatives.
• Evidence of fluctuating capacity — records showing the testator's presentation on different days, including periods of lucidity and confusion.
• Treating doctor's observations — the GP or specialist who knew the testator over time can give evidence about their cognitive trajectory and functioning.

Solicitor file evidence — the Golden Rule

The solicitor who prepares a will for an elderly or unwell testator occupies a critical position. In Kenward v Adams (1975), Templeman J stated what has become known as the "Golden Rule": where a testator is elderly or seriously ill, the solicitor should obtain a medical assessment of testamentary capacity contemporaneous with the will's execution.

When this rule is followed, the solicitor's file will contain:

• A medical report or letter confirming the testator had testamentary capacity
• Detailed attendance notes recording the testator's presentation, understanding, and instructions
• Notes confirming the testator was seen alone and appeared to act freely
• The testator's explanation for any departure from previous testamentary intentions
• Evidence that the testator understood the nature and effect of the will

When the Golden Rule is not followed — where a solicitor prepared a will for an elderly, unwell, or vulnerable testator without obtaining a medical assessment — the court will scrutinise the circumstances closely. The absence of a contemporaneous medical assessment does not make the will invalid, but it may give rise to suspicious circumstances that require explanation.

NSW vs QLD — Key differences

Common mistakes in capacity disputes

• Assuming a dementia diagnosis means lack of capacity. A diagnosis of dementia does not automatically mean the person lacks testamentary capacity. Capacity is assessed at the time of execution — a person with dementia may have lucid intervals during which they can validly make a will. Conversely, a person without a dementia diagnosis may lack capacity due to delirium, medication effects, or other transient causes.
• Relying solely on medical evidence. Medical evidence is important but not determinative. Lay evidence — from family, friends, carers, and witnesses — about the testator's behaviour, comprehension, and expressed intentions is also relevant. The court will weigh all available evidence.
• Delaying the investigation. Medical records may be harder to obtain over time. Witnesses' memories fade. The solicitor's file may be destroyed once retention periods expire. Act promptly to secure evidence.
• Failing to distinguish between eccentricity and incapacity. A person is entitled to make an eccentric, unfair, or even spiteful will — provided they have capacity and their will is not the product of coercion. Unfairness alone is not incapacity.
• Not obtaining the solicitor's file. The solicitor's file is often the single most important piece of evidence in a capacity dispute. Request it immediately.

Frequently asked questions