An introduction to testamentary capacity

What you need to know about assessing testamentary capacity - the ability or understanding needed to make a valid will.

You may be asked to comment on a patient's testamentary capacity where:

  • a living patient or their solicitor asks you to witness the signing of a will, or produce a letter confirming the patient has capacity to make a will
  • you are asked to comment on whether a deceased patient had testamentary capacity when they made a will; for example, as a witness in court proceedings about a disputed will.

In some circumstances, a doctor might face a civil claim or a complaint to the GMC about having witnessed a will or commented on testamentary capacity - so it's important to understand the role you play if doing so.

Legal terminology

  • Testator: the person who makes a will.
  • Codicil: a subsequent addition or amendment to the original will.
  • Testamentary capacity: the capacity, or understanding, required to make a valid will.

Some background - Banks v Goodfellow

Mental capacity is decision-specific. The test of testamentary capacity is set out in the case of Banks v Goodfellow. Although this is an English case, it is a touchstone in all UK jurisdictions including Northern Ireland.

  • A patient with schizophrenia passed his sizeable property estate to his teenage niece.
  • The court held that the validity of the will was unaffected by partial unsoundness of mind; as long as the testator understood what he was doing with his property and affairs at the time the will was drafted and executed, it was valid.
  • The Lord Chief Justice said: "It is essential...that a testator shall understand the nature of the act and its effects; shall understand the extent of the property of which he is disposing; shall be able to comprehend and appreciate the claims to which he ought to give effect; and, with a view to the latter object, that no disorder of the mind shall poison his affections, pervert his sense of right, or prevent the exercise of his natural faculties - that no insane delusion shall influence his will in disposing of his property and bring about a disposal of it which, if the mind had been sound, would not have been made."

In order to have testamentary capacity, the testator must be capable of understanding:

  • the nature and effect of making a will
  • the extent of their estate
  • the claims of those who might expect to benefit from the will.


  • The testator should not have a mental illness that influences them to make bequests that they would not otherwise have made.

The doctor's role

Solicitors in England and Wales will usually follow a golden rule - that the making of a will by an elderly person, or one who has suffered a serious illness, ought to be witnessed or approved by a medical practitioner who "satisfies himself [sic] of the capacity and understanding of the testator, and records and preserves his examination and finding."1

In Scotland, the solicitor drafting the will is responsible for ensuring the testator's capacity. If they're unsure, solicitors should seek the advice of a medical professional (B1.5 Vulnerable Clients Guidance, paragraph nine).

You could be challenged in writing or in the witness box and asked to explain your experience and expertise in assessing testamentary capacity, as well as explaining how you came to your opinion.

It is our experience that even when a doctor is asked to act solely as a witness to the signing of the will, without having had a formal request to assess testamentary capacity, it could be suggested that you have assessed the person involved as having a 'sound mind' to sign the document. If a dispute arises, you might be asked to give evidence.

Assessing testamentary capacity

  • If you're considering witnessing a will or writing a letter about capacity to make a will, think carefully about whether it's appropriate for you to do so.
  • If you do decide to go ahead, take time to make a thorough assessment and keep careful notes.

The following questions might be helpful to use as a reference.

Do you have enough expertise in assessing testamentary capacity?

Work within the limits of your competence and make sure any information you communicate is accurate, not false or misleading (GMC 'Good medical practice', paragraph 89).

You should only write a letter expressing an opinion that a patient is capable of signing a will, or write this in patient records, if you have made an assessment of testamentary capacity that assesses the factors set out in Banks v Goodfellow.

As with any assessment a doctor makes, you should feel be able to justify and explain your decision making if asked to do so at a later date, so consider whether a specialist opinion might be more appropriate.

Do you have enough information about the legal test to be applied?

Make sure you have a good understanding of the legal principles that relate to testamentary capacity. These should be set out for you by the patient's (or their executor's) solicitor.

Do you have enough information about the extent of the estate and potential beneficiaries, in order to discuss these with the patient?

Ideally, a letter of instruction from the patient's solicitor will include information about previous wills so you can discuss with the patient their reasons for including or excluding potential beneficiaries. If it has not been included, it's reasonable to ask the solicitor for this before you assess the patient.

If you decide to go ahead with an assessment of testamentary capacity, you should be aware of the legal test to be applied and check the person understands each of the points above from Banks v Goodfellow.

Set aside adequate time to assess the person thoroughly. You may find it uncomfortable to ask about the extent of the estate, potential beneficiaries, and the patient's choices of who to leave out of a will - but embarrassment is "best not deferred to the witness box, after a patient's death".

Detailed records

Keep detailed, clear and contemporaneous notes when making an assessment of testamentary capacity, and record your opinion. If your assessment is challenged at a later date - for example, if a dispute arises after a patient's death - your notes may be significant.

Keep a note of who else was present during the assessment.

Further information

The GMC has published guidance on assessment of mental capacity, which includes helpful points clarifying the approach to assessing testamentary capacity.

Members can contact us for specific advice. You can also read our guide on assessing mental capacity.


  1. Kenward v Adams (1975), The Times, 20 November 1975

This page was correct at publication on 09/10/2023. Any guidance is intended as general guidance for members only. If you are a member and need specific advice relating to your own circumstances, please contact one of our advisers.

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