Contesting a Will on Grounds of Mental Capacity

To make a valid will, a person must have the mental capacity to understand what they are doing. Where someone made or changed a will while affected by dementia, a stroke, a brain injury or another condition, the will may be invalid. Our specialist solicitors can advise you on whether a will can be challenged on grounds of lack of testamentary capacity.

Call us on 0161 930 5151 or email willdisputeteam@gorvins.com for a confidential conversation about a will you are concerned about.

What is testamentary capacity?

Testamentary capacity is the legal term for the mental ability a person needs in order to make a valid will. The person making the will is known as the testator. Having a diagnosis such as dementia does not automatically mean someone lacked capacity. Capacity is specific to the decision and to the moment the will was made, so the question is always whether the person had the necessary understanding at the time they gave instructions for and signed that particular will.

The Banks v Goodfellow test

The test the courts apply comes from a case decided in 1870, Banks v Goodfellow, and it remains the correct test today. It was confirmed as recently as Clitheroe v Bond in 2021 and Leonard v Leonard in 2024. To have had testamentary capacity, the person must have been able to:

• understand that they were making a will and the effect it would have
• understand, broadly, the extent of the property and assets they were leaving
• appreciate the claims of those they might be expected to provide for, such as family members, even if they chose not to benefit them
• be free from any disorder of the mind or delusion that affected how they disposed of their estate

All four limbs must be satisfied. If any one of them is not met, the person did not have testamentary capacity and the will can be declared invalid.

When can a lack of capacity make a will invalid?

Concerns about capacity often arise where:

• the person had been diagnosed with dementia, Alzheimer’s or another cognitive condition
• the will was made after a stroke, brain injury or serious illness
• the person was heavily medicated, or seriously unwell, when the will was made
• the will was changed late in life in a way that departs sharply from their long-standing wishes
• a new will was made quickly, without proper medical or legal safeguards, in favour of someone who had recently become involved in their affairs

Lack of capacity frequently overlaps with other grounds. If you are also concerned that the person was pressured, our specialists in undue influence can advise, and where a signature or document looks suspicious, see our page on fraudulent and forged wills.

The golden rule

Where a will is made by someone who is elderly or seriously ill, best practice, known as the golden rule, is for the will to be witnessed or approved by a medical practitioner who has assessed the person’s capacity and recorded their findings. The golden rule is guidance rather than a strict legal requirement, and a will is not automatically invalid just because it was not followed. But where it was ignored for a vulnerable person, that can be an important part of the evidence when capacity is later questioned.

Who has to prove capacity?

The starting point is that a properly signed will is presumed to be valid. However, if credible evidence raises a real doubt about the person’s capacity, the burden shifts to the people relying on the will to prove that the person did have testamentary capacity when it was made. The standard of proof is the balance of probabilities. This shifting burden is one reason early, well-organised evidence matters so much, and why these claims are best handled by an experienced contentious probate solicitor.

What evidence is needed?

Capacity claims are decided on evidence, and the most useful sources usually include:

• the person’s medical records and GP notes around the time the will was made
• the will file and attendance notes from the solicitor or will writer who prepared it
• any contemporaneous capacity assessment
• witness accounts from family, friends and carers about the person’s condition at the time
• a retrospective report from a medical expert, such as a psychiatrist, though the court treats this as opinion rather than the final word

What happens if a will is found to be invalid?

If a will is set aside for lack of capacity, the estate does not pass to whoever challenged it. Instead, the most recent valid earlier will takes effect. If there is no earlier will, the estate is distributed under the intestacy rules, which set a fixed order of who inherits.

Is there a time limit?

There is no strict statutory deadline for challenging a will’s validity on capacity grounds, but you should act quickly. Medical records and witness recollections deteriorate over time, and once an estate has been distributed it is much harder to put things right. If you suspect a problem, the first protective step is often to enter a caveat at the Probate Registry to pause the grant of probate while matters are investigated. If your concern also involves a claim for reasonable financial provision, note that Inheritance Act claims carry a strict six-month deadline from the grant of probate.

How Gorvins can help

Our Will Disputes and Contentious Probate team acts for both those challenging and those defending a will where capacity is in question. We can:

• advise quickly on whether a capacity challenge is realistic
• enter a caveat to pause probate while we investigate
• obtain medical records, the will file and capacity assessments
• instruct appropriate medical experts
• bring or defend a claim to have the will declared valid or invalid
• resolve disputes through negotiation or mediation where possible, and litigate when necessary

Where the concern is broader, our page on contesting a will explains all the grounds on which a will can be challenged.

Gorvins is a Legal 500 recognised firm based in Stockport, acting for clients across Greater Manchester, the North West and nationally.

Call us on 0161 930 5151, email willdisputeteam@gorvins.com, or complete the enquiry form below and we will call you straight back.

Mental capacity and wills FAQs

Can a will made by someone with dementia be challenged?

Possibly. A dementia diagnosis does not by itself make a will invalid, because capacity is judged at the moment the will was made. If the evidence shows the person did not meet the Banks v Goodfellow test when they made that particular will, it can be challenged.

What is the test for mental capacity to make a will?

The Banks v Goodfellow test. The person must have understood that they were making a will and its effect, understood the extent of their assets, appreciated the claims of those they might provide for, and been free from any disorder of the mind affecting their decisions. All four limbs must be met.

Who has to prove the person lacked capacity?

A properly signed will is presumed valid. But if credible evidence raises a real doubt about capacity, the burden shifts to those relying on the will to prove the person did have capacity, on the balance of probabilities.

What is the golden rule?

It is best-practice guidance that a will made by an elderly or seriously ill person should be witnessed or approved by a medical practitioner who assesses and records their capacity. It is not a strict legal requirement, but ignoring it for a vulnerable person can be significant evidence if capacity is later challenged.

How long do I have to challenge a will on capacity grounds?

There is no strict statutory deadline for a validity challenge, but you should act promptly as evidence fades and estates get distributed. Related Inheritance Act claims carry a strict six-month deadline from the grant of probate.

What happens if the will is declared invalid?

The estate passes under the most recent valid earlier will, or under the intestacy rules if there is no earlier will. It does not automatically go to the person who challenged the will.