For a will to be valid, the testator must have had testamentary capacity at the time it was made. Testamentary capacity refers to the mental ability of the testator to make a valid will.
The test for capacity
Being diagnosed with a condition such as dementia is not conclusive as to capacity. Capacity is time and task specific, and a person’s capacity may decline over time or may fluctuate, such that they may have capacity one day and not on the next. It can be difficult to determine the precise point that someone loses capacity, particularly when their condition involves a gradual deterioration. As noted in the case of Boyse v Rossborough [1857], “there is no possibility of mistaking midnight for noon, but at what precise moment twilight becomes darkness is hard to determine”.
Tests for capacity are issue specific. The legal test for capacity to make a will is derived from the case of Banks v Goodfellow (1870), which requires the testator to:
- Understand the nature and effect of making a will;
- Comprehend the extent of the property being disposed of;
- Recognise the claims to which they ought to give effect; and
- Not be suffering from any disorder of the mind that influences their decisions regarding the distribution of their estate.
The importance of evidence
Evidence is key in disputes concerning capacity. Medical records, witness testimonies, and expert opinions play a significant role in establishing whether the testator had the requisite capacity at the time the will was made.
In the case of Tucker v Felton-Page & Ors [2025], the validity of a will made in 2013 was challenged on various grounds, including a lack of testamentary capacity. Ms Moore who died in 2014 was suffering from a visual impairment and dementia at the time her 2013 will was made. The validity of her will was challenged by her niece, who had an interest in Ms Moore’s estate under an earlier 2006 will.
Each party instructed medical experts to opine retrospectively on the whether the testator had capacity at the time the will was made, and both experts ultimately agreed that she did not. In addition, the “Golden Rule” had not been followed. The Golden Rule is that, where a testator is elderly or unwell, medical evidence should be obtained to confirm capacity at the time the will is made. A failure to follow the Golden Rule is not conclusive as to whether a will is valid, and medical evidence does not usurp the authority of the court to determine the issue. However, this was compelling evidence which, when considered with the other available information, was sufficient to persuade the court that the will was not valid due to the testator lacking capacity.
Recommendations from the Law Commission
The Law Commission's report on modernising wills was published in May 2025. In 2005 the Mental Capacity Act (“MCA 2005”) introduced a test for capacity which applies to cases before the Court of Protection when determining whether someone has capacity to make decisions concerning their affairs during their lifetime.
For the purposes of the MCA 2005, a person lacks capacity in relation to a particular matter if at the material time they are unable to make a decision for themselves in relation to that matter because of an impairment of, or a disturbance in the functioning of, the mind or brain. Under section 3(1) of the MCA 2005 a person is unable to make a decision for themselves if they are unable to:
- understand the information relevant to the decision;
- retain that information;
- use or weigh that information as part of the process of making the decision; or
- communicate his decision (whether by talking, using sign language or any other means).
While the test under the MCA 2005 is very similar to that set out in Banks v Goodfellow, the Law Commission’s view is that for consistency and to avoid confusion, it is better to have only one applicable test, so the MCA 2005 test should also apply when assessing capacity to make a will.
Case law has established that there is a presumption that someone has capacity to make a will unless it is shown that they do not, something that is expressly set out in the MCA 2005. The Law Commission recommends that the statutory presumption under the MCA 2005 also applies to the making of wills.
Conclusion
Even if the recommendations from the Law Commission are implemented, challenging the validity of a will based on a lack of capacity will remain a complex and nuanced area. Understanding the legal framework, gathering robust evidence, and staying informed about recent developments are essential to navigate these challenges.
About the author
Kate Salter is a Senior Associate who specialises in trust, estate and Court of Protection disputes. Her experience in the field of estate disputes includes challenges to the validity of wills (including claims based on a lack of testamentary capacity, want of knowledge and approval, fraud, forgery and undue influence), and claims under the Inheritance (Provision for Family and Dependants) Act 1975.
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