“Testamentary capacity” is essential to the valid making and signing of a Will. In basic terms, it means that the will-maker must have the mental and physical capability to make a Will.

Testamentary capacity is very important, as if a will-maker lacks capacity, their Will can be challenged in a court and quite possibly be declared invalid.

To determine whether a person had testamentary capacity when making a Will, the courts will look at all the facts of the surrounding circumstances and decide on the balance of probabilities whether the will-maker had capacity. These can include both physical and mental illnesses which may have taken a toll on the will-maker.

Despite medical evidence being a large contributor to whether a person had testamentary capacity, this is not the only evidence that a court will consider. The court may also consider evidence from the legal professionals who drew up the will, and other persons with knowledge of the will-maker. 

The essential elements to prove testamentary capacity were determined in the case Banks v Goodfellow. The person making the Will must:

  1.     Understand the nature and effect of making a Will;
  2.     Understand the extent of his or her estate;
  3.     Have knowledge of the claims of those who might expect to benefit under the Will; and
  4.     Not have a mental illness that influences making gifts in the Will that would not otherwise have been                 made.

A mental illness by itself may not be enough to find that a person did not have testamentary capacity. For example, the courts have found that a person was of sound mind, despite suffering from illnesses such as dementia.

On the other hand, the courts have found that a person with terminal cancer did not have testamentary capacity, due to the toll that medication and other treatments had taken on his mind and subsequent decision-making capability.

A person may or may not have testamentary capacity when they have episodes of confusion or lack of understanding. The essential question surrounds the will-maker’s capacity at the time the Will was actually made.

A will-maker may not have testamentary capacity even if the content of the Will itself seems rational. The courts will look at the will-maker themselves and their capacity for understanding the document, rather than the contents of the Will itself.

It is usually recommended that a legal professional obtains a medical certificate for the will-maker at the time of the making of the Will, especially if there are concerns surrounding testamentary capacity. The certificate should state whether or not the will-maker had capacity, and will be very persuasive in court if the Will is challenged.

If no issue is raised, there will be a presumption that the will-maker had testamentary capacity. However, if an issue of testamentary capacity arises, the person that seeks to prove the Will as authentic must provide sufficient evidence of capacity.

If you are considering making or altering a Will, it pays to seek advice from a professional with experience in the area.


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Author Sarah Jamieson and Hunter Flanagan-Connors