An introduction to testamentary capacity

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

  • During their life, a patient or their solicitor asks you to witness the signing of a will, or to produce a letter to confirm the patient has capacity to make a will.
  • After a patient has died, you are asked to comment on whether the patient had testamentary capacity at the time they made a will, for example as a witness in court proceedings relating to a disputed will.

In some circumstances, a doctor may 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, should you undertake such an assessment.

Legal definition

Testator/testatrix – the person who makes a will.
Codicil – a subsequent addition or amendment to the original will.

Testamentary capacity is the capacity, or understanding, required by the testator/testatrix to make a will.

Banks v Goodfellow

Mental capacity is decision-specific and the test of testamentary capacity is set out in the case of Banks v Goodfellow.

  • A schizophrenic 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; so long as the testator understood what he was doing with his property and affairs at the time the will was drafted and executed, then 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 his or her estate
  • the claims of those who might expect to benefit from the will.


  • The testator should not have a mental illness that influences him or her to make bequests that he or she would not otherwise have made.

The doctor's role

Solicitors 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 of the capacity and understanding of the testator, and records and preserves his examination and finding.'1

If you witness a will, you will be inferred to have made an assessment of the testamentary capacity of the testator and 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.

Assessing testamentary capacity

If you are considering witnessing a will or writing a letter about capacity to make a will, at the request of a patient or anyone else on a patient's behalf, take time to consider carefully whether it is appropriate for you to agree to take on the role. If you do decide to go ahead, take time to make a thorough assessment and keep careful notes.

Use the following questions as a reference:

Do you have sufficient expertise in assessing testamentary capacity?

Work within the limits of your competence and take reasonable steps to ensure anything you write or sign is verifiable.

If you witness a will or write a letter expressing an opinion that a patient is capable of signing a will, it will be inferred that you have made an assessment of testamentary capacity.

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 in order for you to be able to discuss with the patient their reasons for including or excluding potential beneficiaries. If it has not been included, then it is reasonable to ask the solicitor for this prior to you assessing the patient.

If you do decide to go ahead with an assessment of testamentary capacity, you should be aware of the legal test to be applied and check that 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 about the patient's choices regarding who to leave out of a will. However, 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. Should your assessment be challenged at a later date, for example if a dispute arises following a patient's death, your notes may be of great significance.

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

Further information

The BMA and the Law Society have published guidance for doctors and lawyers on assessment of mental capacity, which includes helpful points clarifying the approach to assessing testamentary capacity.

For specific advice relevant to your individual circumstances, contact the MDU.


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

This page was correct at publication on 06/06/2018. 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.