Australia boasts one of the world's highest life expectancies as highlighted by the Australian Institute of Health and Welfare. Several factors contribute to this including a developed healthcare system, public health initiatives and a high standard of living. However, in 2024 dementia was the second leading cause of death in Australia as documented by Dementia Australia. It is projected that the number of Australians living with dementia will double by 2054. With stats like these, it is likely we will observe an increase in estate disputes, particularly regarding a person's testamentary capacity to make or alter their Will.

What is "Testamentary Capacity"?

Testamentary capacity refers to an individual's legal and mental capability to create or modify their Will. There is a general presumption that a person has this capacity unless evidence suggests otherwise. Testamentary capacity is not limited to dementia diagnoses and can also be affected by psychiatric disorders, neurological conditions or other medical issues affecting a person's mental faculties. The existence of a diagnosis of any of these conditions does not automatically make a Will invalid.

To ascertain whether a testator (the person drafting their final Will and testament) maintains testamentary capacity, Australian courts rely on the landmark 1870s case of Banks v Goodfellow. This case establishes the foundational legal framework for evaluating and confirming testamentary capacity.

Criteria to be met includes the following:

  1. The person must understand the nature of making a Will and its effects;
  2. Understand the nature and extent of their assets and property;
  3. Be able to comprehend and appreciate the claims to which they ought to give effect to (eg know the people they may be expected to provide for in their Will); and
  4. They are not suffering from a disorder of the mind or any insane delusions which may influence their testamentary dispositions.

If the above test is not satisfied, a person's Will may be invalid. If a Will is invalid, this means their penultimate Will then becomes their last Will and testament. If they do not have a previous Will, they will be considered to have died intestate (as if they did not have a Will), and their estate will be administered in accordance with South Australia's intestacy laws. For more information, you can read our article on intestate Wills via this link.

How do I contest a Will based on testamentary incapacity?

If you believe a person lacked testamentary capacity to make or change their Will, you need to provide evidence to support this claim. If a grant of probate has not been issued in the estate, you may consider lodging a caveat to prevent probate being issued. This will allow time to gather medical evidence of a person's testamentary incapacity. It is important to seek legal advice regarding the procedure and time limit restrictions when contesting the validity of a Will.

Only those with sufficient interest in an estate have standing to contest a Will. This could include heirs or beneficiaries, creditors, dependents or close relations or spouses or domestic partners.

How to prevent your Will being contested

If you decide not to include certain family members or dependents in your Will or if you are planning to distribute your assets unevenly among your beneficiaries, this could potentially lead to disagreements down the road after you have died. You should be aware that these decisions might be subject to later discussions or disputes, so careful consideration and seeking legal advice will be helpful in avoiding future arguments or a successful claim to invalidate your Will.

The content of this article is intended to provide a general guide to the subject matter. Specialist advice should be sought about your specific circumstances.