Challenge a Will: Mental Capacity Grounds UK

What this document is

Mental capacity, in the context of wills, refers to whether the person making the will (the testator) had the mental ability to understand what they were doing at the time they signed it. The long-standing legal test comes from a Victorian case called Banks v Goodfellow, and it still shapes how courts approach these disputes today.

In broad terms, the testator needed to understand that they were making a will and what effect it would have, to grasp the rough extent of what they owned, to appreciate who might reasonably expect to benefit, and to be free from any disorder of the mind that twisted their decisions. Capacity is assessed at the moment the will was made, not before or after.

Someone can have a diagnosis of dementia and still have had capacity on the day they signed, just as someone with no diagnosis might have been too confused or medicated to meet the test. This is why these cases turn so heavily on the specific facts and the available evidence.

How to use this document

1. Gather what you already know. Start by pulling together the basic facts: when the will was signed, who drafted it, who witnessed it, and what the testator's health was like at that time. Note any earlier wills, promises made to family members, or sudden changes in how the estate was divided. This picture helps you judge whether there is a genuine basis for a challenge or whether the will simply reflects decisions you disagree with.
2. Request the will file from the solicitor. If a solicitor prepared the will, their file often contains attendance notes, capacity assessments, and correspondence that can be decisive. You can ask for this under the Larke v Nugus principles, which encourage solicitors to share information where the validity of a will is in question. The notes may either support your concerns or confirm that proper checks were carried out.
3. Obtain the medical records. Access to the deceased's medical records is usually essential, as they can show diagnoses, medication, hospital admissions, and clinical observations around the time the will was signed. A personal representative or someone with a legitimate interest can request these. The records are then typically reviewed by a medical expert who can comment on likely capacity at the relevant date.
4. Enter a caveat at the Probate Registry. If probate has not yet been granted and you want to prevent the estate being distributed while the dispute is resolved, you can enter a caveat. This lasts for a set period and can be renewed. It buys time to investigate, but it is a formal step, and you should only use it where you genuinely intend to pursue a challenge.
5. Take advice on the strength of your case. Capacity disputes are evidence-heavy and the costs can escalate quickly. Before issuing a claim, it is worth getting an honest read on how strong the evidence is, what a likely earlier will would say, and whether mediation or a negotiated settlement might be a better path than contested litigation.

Common questions