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Contesting a will on the grounds of mental capacity

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Posted by Martin Oliver on 17 May 2013

Martin Oliver - Contesting a Will Lawyer
Martin Oliver Partner

One of the grounds for challenging the validity of a will is that the person who made the will did not have the relevant mental capacity to understand his actions.  

Testamentary capacity

A person making a will must be of “sound mind, memory and understanding” when making a will. The law relating to whether a person has sufficient mental capacity to understand the content of his will was established in the case of Banks v Goodfellow [1869-70] which stated that the testator must:

  • understand the nature of the act and its effects
  • understand the extent of the property of which he/she is disposing
  • be able to comprehend and appreciate the claims to which he/she ought to give effect  
  • and must not be effected by any “disorder of the mind” that shall “poison his affections, pervert his sense of right, or prevent the exercise of his natural faculties and that no insane delusion shall influence his will in disposing of this property and bring about a disposal of it which, if the mind had been sound, would not be made”.

The factors referred to in Banks v Goodfellow are considered in more detail below.

Understand the nature of the act and its effects

The law does not call for a perfectly balanced mind. Just because a person making a will was moved by “frivolous, mean or even bad motives” will not make a will invalid. A person is entitled to disinherit his children for reasons of spite without such wishes being challenged on the grounds of mental capacity. This is obviously subject to the individual having “sound mind, memory and understanding” at the time the will was made. The question as to whether a person has the relevant mental capacity is a factual question which is often determined by medical evidence. However, the evidence of close friends and family is also relevant and a person can be found to be lacking mental capacity based upon their evidence alone.  

When contesting a will, problems arise with issues concerning mental capacity where a disease affects the mind over a period of time, e.g. Alzheimer’s. In such patients it is often the case that on some days they understand matters and on others their memory is lacking. To succeed with contesting a will, it must be shown at the time the will was executed, the testator did not have the capacity to make a will.  

Understand the extent of the property

A testator need only have the capacity to understand the extent of his property. It is not the case that a testator has to have a detailed knowledge of all of his assets/monies. For example if a testator has a broad idea of his assets but is not able to give specifics, it will not be possible to successfully contest a will on the basis of mental capacity. Cases in which the testator did not understand the extent of the property are very rare. Where this specific heading is raised, it is often in support of other matters concerning a testator’s capacity.

Comprehend and appreciate the claims to which he/she ought to give effect

If a testator did not consider leaving part of their estate to a close family member or did not consider a claim against the estate, this may be an indication that the person lacked the necessary mental capacity to understand their actions and it may be possible to contest a will. Such claims may include those pursuant to the Inheritance (Provision for Family and Dependents) Act 1975, details of which are included in Part 8 of this series of articles.  

Contesting a will: presumption of capacity

Mental capacity will be presumed if the testator left a will which appears to be rational and contains no irregularities.

If, however, having seen the testator’s medical records and spoken to close family members, it is established that the testator has a history of mental illness/confusion or memory loss, it will be for those persons seeking to rely on the document to establish capacity (see Vaughan v Vaughan [2005]). For example, if an executor named in such a will is insistent that the will is valid, it will be for the executor to prove that the testator had the necessary testamentary capacity. 

Preliminary steps

If you have grounds to suspect that the testator did not have the necessary testamentary capacity to understand the content of their will, it is important to take action and legal advice as soon as possible.  You may wish to enter a caveat with the Probate Registry to prevent a Grant of Probate being taken out and the assets of the estate distributed.  You can also contact the solicitors who prepared the will and request details regarding the will’s preparation and locate the witnesses to the will to find out the circumstances surrounding the execution.  Try and obtain the testator’s medical records to establish whether the individual was suffering from any illnesses.  Even if the medical records are not supportive of a claim concerning mental capacity, if there are witnesses confirming the individual lacked such capacity, it may be possible to contest a will. 


Where a will is successfully disputed and the court confirms the will is invalid, if there is not an earlier valid will, then the testator’s estate will be distributed according to the intestacy rules. 

Other articles in the series: 

About the author

Martin specialises in inheritance disputes such as contesting a will and litigation involving wills and trusts.

Martin Oliver

Martin specialises in inheritance disputes such as contesting a will and litigation involving wills and trusts.

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