This guide is maintained as a current resource for September 2026 and covers only the laws of England and Wales. Information is for general guidance, not legal advice. Consult a qualified solicitor for advice specific to your situation.
Comprehensive guide explaining what testamentary capacity is under English law, how courts assess mental ability to make a will using the Banks v Goodfellow test, implications for vulnerable individuals, capacity assessments and risks in will challenges.
Testamentary capacity is the legal term that describes whether a person has the mental ability to make or change a valid will. In the context of wills law in England and Wales, testamentary capacity is a fundamental requirement for validity: if someone lacks capacity when they execute a will, that document may be declared invalid and treated as if it never existed, potentially leading to disputes, claims and distribution under intestacy rules. This article explains what testamentary capacity means, the legal tests used to assess it, how it applies in practice, and related legal processes and risks.
What is Testamentary Capacity?
Testamentary capacity refers to a person's legal and mental ability to understand and make decisions about how their estate should be distributed on their death. It is distinct from general mental capacity: someone may have difficulties in other aspects of life but still possess testamentary capacity at the relevant time. If a will is made or altered by someone without sufficient capacity, that will may not be legally effective.
The Legal Test: Banks v Goodfellow
The governing test for testamentary capacity in England and Wales comes from the 1870 case of Banks v Goodfellow, a landmark decision in wills law that remains authoritative. Under this test, a person must, at the time they make a will:
- Understand the nature and effect of making a will, including that it is a document giving instructions for the distribution of their estate.
- Understand the extent of the property they are disposing of, even if they cannot recall every detail.
- Comprehend and appreciate the claims of those who might reasonably expect to benefit, such as close family members.
- Not be suffering from a disorder of the mind or delusion that influences how they dispose of their property in a way they would not have done if of sound mind.
The Banks v Goodfellow test remains central even though broader capacity law exists (such as the Mental Capacity Act 2005, which governs capacity for most decision‑making during life). Courts have confirmed that Banks v Goodfellow continues to apply specifically to wills validity, and that a rational will prepared professionally is generally strong evidence of capacity.
How Capacity Is Assessed in Practice
Timing of Assessment
Capacity must be present when instructions are given to prepare the will and when the will itself is signed. A person's mental state can change over time, so capacity on one occasion does not necessarily prove capacity at another. If someone's capacity is uncertain due to illness or cognitive decline, it may be sensible to seek independent evidence at the time the will is made.
Professional Assessments
Where there are concerns about a person's ability to meet the Banks v Goodfellow criteria, a testamentary capacity assessment can be conducted by qualified professionals, such as doctors, psychiatrists or experienced solicitors. These assessments involve evaluating understanding of the will, knowledge of assets and awareness of potential beneficiaries. A detailed report can provide contemporaneous evidence useful for protecting the will against later challenges.
The “Golden Rule”
Legal practice often refers to the Golden Rule (from older case law) recommending that, where doubt exists (for example, due to serious illness or advanced age), the testator should be examined by a medical professional at the time of signing. This helps create reliable evidence of capacity and can reduce the risk of disputes.
Capacity and Vulnerable Individuals
Dementia and Cognitive Impairment
A diagnosis such as dementia or brain injury does not automatically mean a person lacks testamentary capacity. The key issue is whether the testator meets the legal criteria at the relevant moment. Many people with early‑stage cognitive conditions retain capacity to make or amend a will if they understand the implications of their decisions.
However, where there are genuine concerns, professional assessment and clear documentation are important to protect the validity of the will and the testator's intentions.
Statutory Wills and the Court of Protection
If a person lacks the capacity to make a will, it is sometimes possible for a statutory will to be made on their behalf. This is an order made by the Court of Protection under the Mental Capacity Act 2005 in the person's best interests, allowing the court to authorise a will for someone who no longer has capacity themselves. This process requires formal application and evidence, and differs from a will personally signed by the individual.
Challenges and Will Validity
Grounds for Challenge
A will may be challenged if it is alleged that the testator lacked testamentary capacity at the relevant time. Such challenges often arise in contentious probate claims, where potential beneficiaries argue that cognitive impairment or delusion affected the testator's decisions.
Evidence for capacity (or lack of it) may include medical records, witness statements, professional capacity assessments, and the circumstances of the will's preparation. Courts will weigh all available evidence to determine whether the Banks v Goodfellow criteria were met.
Practical Considerations for Avoiding Disputes
Will makers and their advisers can take practical steps to reduce the risk of successful challenges:
- Ensure the testator understands the nature and effect of the will before signing.
- Use independent witnesses and professionals familiar with capacity assessment.
- Obtain contemporaneous medical evidence where appropriate.
- Keep records of discussions about the will and any professional assessments.
Common Questions
Is testamentary capacity the same as general mental capacity?
No. A person may lack general capacity for some decisions but still have testamentary capacity to make a will, provided they satisfy the Banks v Goodfellow criteria at the relevant time.
Does the Mental Capacity Act 2005 apply to wills?
The Mental Capacity Act 2005 governs most decisions made while a person is living, but for the validity of wills, the common law test from Banks v Goodfellow remains the primary standard. Courts may refer to the Mental Capacity Act when considering statutory wills, but the historic test continues to govern will validity.
Key Takeaways
Testamentary capacity is a key legal requirement for a valid will in England and Wales. The established legal test from Banks v Goodfellow requires that the person making the will understands the nature and effect of their decision, the extent of their estate and the claims of potential beneficiaries, and is free from mind disorders or delusions that affect their choices. Capacity is assessed at the time of will execution, and professional assessment and documentation can help protect wills against later challenges. Understanding these principles helps testators, families and professionals make or review wills with greater confidence and legal certainty.
