To make a Will, you must have “mental capacity” – and sometimes Wills are challenged because it is thought that the person who made the Will (the testator) did not have the required mental capacity at the time. Logically, we therefore need to know what is meant by mental capacity and what standard is required.
Perhaps surprisingly, in the context of making a Will, “capacity” does not mean the definition set out in the Mental Capacity Act 2005. The courts have confirmed this in cases like James v James [2018] and Walker v Badmin [2014] (Re Walker (Deceased)).
More recently, the High Court in Clitheroe v Bond [2021] explicitly held that testamentary capacity should be assessed using the common-law test in Banks v Goodfellow, not the test in the Mental Capacity Act. The reason is that the Mental Capacity Act is designed for decisions made by living persons (and how others can make decisions for someone lacking capacity), which is very different from the retrospective question of whether a deceased person had capacity when making their Will. Such retrospective evaluations fall outside the scope of the Mental Capacity Act.
So, what is the relevant test? The legal test comes from a very old case – Banks v Goodfellow (1870) LR 5 QB 549. Banks v Goodfellow remains the seminal standard for assessing testamentary capacity, affirmed repeatedly up to Leonard v Leonard [2024]. According to Banks v Goodfellow, when a person makes their Will, they must:
- Understand what they are doing. (They need to appreciate that they are making a Will and what that means in general terms.)
- Understand the extent of the property they are disposing of. (They should have a sense of what assets and estate they have, even if not knowing precise values.)
- Understand and appreciate the claims to which they ought to give effect. (They should be able to comprehend who might have a moral claim on their estate – e.g. close family – even if they choose not to benefit them.)
- Not be affected by any “insane delusion” influencing the disposal of their property. (In other words, no mental disorder or fixed false belief should pervert their sense of right or judgment in making bequests.)
The last point about “insane delusions” has been clarified in modern cases. A simple mistaken belief that could be corrected by evidence will not amount to an insane delusion. The false belief must be irrational and fixed – something the testator firmly believes despite all reason, and which affects the Will. In Clitheroe v Bond [2021], the High Court explained that deciding if a belief was a delusion requires a holistic look at factors like the nature of the belief, how it arose, whether it persisted despite contrary evidence, and how long it was held.
Over the years, courts have developed and explained the Banks v Goodfellow test further. For example, in Key v Key [2010] EWHC 408 (Ch), the court highlighted that a testator must be able to exercise their powers of decision-making – here, an elderly man’s grief impaired his ability to make rational decisions shortly after his wife’s death, so his Will was invalid. And in Simon v Byford [2014] EWCA Civ 280, the Court of Appeal confirmed that the test focuses on the potential capacity to understand, which is not the same as memory. In other words, forgetting details (such as the content of a prior Will or the reasons for an earlier gift) does not bar testamentary capacity, so long as the person can understand what they are doing at the time.
The testator must understand what they are disposing of in the current Will, but need not recall the “collateral” reasons for their previous decisions. A lack of memory about why an earlier arrangement was made – or an inability to foresee all consequences of changing it – does not itself negate capacity, as long as the testator can grasp the essentials of the new Will.
Modern developments:
In recent years there was debate about whether the Banks v Goodfellow test should be updated in light of the Mental Capacity Act 2005. In Baker v Hewston [2023] EWHC 1145 (Ch), a judge suggested that the common-law test and the MCA criteria could “be used concurrently,” with the MCA serving as a cross-check to the traditional Banks factors. If the two tests would yield different results, that discrepancy should prompt further scrutiny of capacity. This pragmatic approach – effectively using the MCA’s more detailed criteria (impairment of mind, inability to understand/retain/weigh information, etc.) as a check on the old rule – generated discussion and some concern that it might complicate things.
However, the debate has since been put to rest. In Leonard v Leonard [2024] EWHC 321 (Ch), the High Court firmly reinforced that Banks v Goodfellow remains good law, having “stood the test of time”. Mrs Justice Joanna Smith in Leonard reasserted that the Banks criteria are the “yardstick” for retrospectively assessing capacity. In that case, the judge went through each of the four limbs in detail, providing an authoritative summary of how courts should apply them in today’s context. Notably, the judgment acknowledged modern medical understanding – for instance, recognising that long-term conditions like dementia can fall within the fourth limb (a “disorder of the mind” that may impair capacity) just as readily as short-term episodes of insanity or delusion. The first limb was also clarified: the testator must be able to understand the specific Will’s effect, not just the concept of a will in abstract. In short, Leonard v Leonard has become a leading recent authority that reaffirms the Victorian test with modern sensibilities.
It is presumed the testator has capacity
Where a Will is properly executed and is rational on its face, there is a legal presumption that the person making it had mental capacity. What does that mean? Essentially, the starting point is that the testator is assumed to be competent. Anyone challenging the Will must produce evidence to raise a real doubt about capacity – otherwise the court will take it as given that the testator did have capacity. This rule originates from cases like Symes v Green (1859), and the principle still holds today. If the objector does put forward sufficient evidence against capacity, that rebuttal of the presumption causes the burden of proof to shift. The court will then require those who want the Will upheld (the propounders of the Will) to prove affirmatively that the testator had sound mind when making it. In other words, once real doubt is raised, the onus is on the Will’s proponents to demonstrate capacity on the balance of probabilities.
Importantly, the Will itself should appear lucid and “ordinary.” If a Will was absurd or irrational in its provisions, the presumption might not arise in the first place – eccentric or unintelligible bequests could themselves be evidence of a lack of capacity. But assuming the Will isn’t bizarre on its face, the law gives the testator the benefit of the doubt until some contrary evidence is produced.
Another key point is the role of those who assisted in the Will’s preparation. Where the Will has been made under the guidance of an experienced solicitor who observed the testator and recorded that they had capacity, it is a very strong thing to overturn that Will. Case law has long held that a duly executed will, prepared by an independent professional who judged the testator to be competent, should only be set aside “on the clearest evidence of lack of capacity” (as stated in Hawes v Burgess [2013] EWCA Civ 74 and echoed in Leonard v Leonard). In practical terms, if a lawyer followed best practices – perhaps even invoking the “Golden Rule” of obtaining a medical opinion for an elderly or ill testator – then the challenger faces an uphill battle. The standard of evidence to rebut capacity in such a scenario is high.
However, this does not mean a solicitor’s involvement is an absolute shield. The court will examine how conscientiously the solicitor (or other professional will-drafter) actually assessed the testator’s capacity. Leonard v Leonard is instructive on this point. In that case, the Will was prepared by a chartered legal executive (a tax adviser employed at a law firm) who unfortunately showed no real awareness of the testator’s capacity issues. Her notes were scant and she did not adequately probe his understanding. As a result, the judge gave her testimony little weight. The judgment endorsed the view from an earlier case (Re Ashkettle [2013]) that any opinion a solicitor forms on a client’s capacity is only as good as the foundation it’s built on – if it’s not based on a *proper assessment and accurate information, it is “worthless.” In short, while a lawyer’s affirmation of capacity is powerful evidence, it can be undermined if the lawyer did not actually do their job in checking capacity. Those seeking to challenge a Will should not lose hope merely because a professional was involved, especially if there are signs the professional was lax.
Recent appellate case law also reaffirms how evidence should be weighed in these disputes. The Court of Appeal’s decision in Hughes v Pritchard [2022] EWCA Civ 386 is a good example. In that case, the testator’s longtime solicitor oversaw the Will and believed the testator was capable (even obtaining a GP’s compliance with the Golden Rule at the time), whereas a retrospective expert report (and the GP’s later, revised view) cast doubt on capacity. The Court of Appeal decisively overturned the first-instance decision that had favored the retrospective medical evidence. It emphasised that the contemporaneous observations of an experienced solicitor can be more probative than a doctor’s opinion given after the fact. The court noted that medical evidence is certainly relevant, but it is just one part of the overall picture.
Ultimately, testamentary capacity is a legal question for the judge to decide, not a medical diagnosis. A doctor’s assessment “feeds into” the legal test; it does not single-handedly determine it. In Hughes v Pritchard, the presence of a detailed, context-rich file from the solicitor (with notes of the testator’s demeanor and understanding) was given substantial weight, whereas the later second-guessing by the GP was viewed with caution. This case serves as a reminder that quality contemporaneous evidence of the testator’s capacity (for example, notes by the drafting lawyer or others present) can be crucial in upholding a Will, even if some expert later has doubts.
What does this mean for you?
If you are considering challenging the validity of a Will on the basis that the testator lacked mental capacity when the Will was made, you will need to gather solid evidence of the testator’s mental state at the time of execution. The focus is on the situation at the time the person made the Will. Relevant evidence can include medical records, expert opinions, witness statements from those who interacted with the testator, and any notes or recordings made by the solicitor or other professionals involved in the Will’s preparation.
It’s important to remember that a medical diagnosis (or lack thereof) is not, by itself, determinative. For instance, a diagnosis of dementia alone is not an automatic bar to making a valid Will – dementia affects people differently and progresses at varying paces. Someone in the early stages of Alzheimer’s might well still have capacity to understand what a Will is and what they want to do with their estate. On the other hand, even without a formal diagnosis, a person could lack capacity due to a temporary disturbance (for example, an acute delirium or a grief-induced impairment as in Key v Key). The courts will look at functionality – what matters is whether the testator could understand, decide, and communicate their wishes at the material time, not what their medical label was.
When presenting a case of alleged incapacity, you might include evidence of any condition affecting the mind or brain (such as dementia, severe mental illness, intellectual disability, the influence of substances, etc.), but you must tie it to how that condition actually impaired the testator’s understanding or decision-making regarding the Will. Similarly, if the testator’s behavior was observed around that time (e.g. episodes of confusion, forgetfulness, irrational statements), those observations can be very relevant. Lack of a formal diagnosis doesn’t prevent a challenge – the court will consider lay evidence of a person’s mental functioning too.
Recent cases like Leonard v Leonard [2024] illustrate how the court approaches these disputes: the judge will take a holistic view of all the evidence. Expert psychiatric opinions, while useful, are not conclusive – as one judge put it, the Banks v Goodfellow criteria “are not matters that are directly medical questions, but are matters for common sense judicial judgment” based on all the evidence. The court will consider medical testimony alongside other facts, such as the testator’s statements and actions, contemporaneous notes from the will-drafting process, and the overall complexity and consistency of the Will itself. Ultimately, it is for the judge to decide, on the balance of probabilities, whether the testator had the capacity as defined by Banks v Goodfellow.
In practical terms, if you suspect a loved one lacked capacity when making a Will, you should act promptly to gather relevant information. This might include obtaining medical records (with appropriate authority), talking to the lawyer who drafted the Will (they may have insight or notes on the testator’s apparent capacity), and interviewing friends or caregivers who saw the testator around that time. Bear in mind that challenging a Will can be emotionally and financially taxing, and courts encourage parties to seek a resolution (for example, through mediation) if possible. Nonetheless, the law provides a mechanism to set aside a Will that is not truly reflective of a person’s intentions due to impaired mental capacity. The enduring message of these cases is that the quality of the evidence will make all the difference. If capacity is in doubt, building a strong, evidence-based picture of the testator’s mind at the time of the Will is crucial to the success of the challenge (or, from the opposite perspective, to defending the Will).
Jennifer Wiss-Carline is a practising Solicitor regulated by the SRA and a Chartered Legal Executive (FCILEx), bringing over two decades of experience to her practice. Specialising primarily in Private Client law, Jennifer expertly handles matters including Wills, Inheritance Tax and Estate planning, Lasting Powers of Attorney for individuals and businesses, Deputyship Orders and more.
