The RMB Wills & Estates & Disputed Wills Division explains how to contest a Will on the grounds of incapacity.
If you believe a Will does not reflect the true wishes of someone who has passed away because they didn’t have the mental capacity to make it, you can challenge it on the grounds of incapacity.
It’s a way to make sure the Will was made with a clear mind and genuine understanding.
To challenge a Will on these grounds, you need to show that the person who made the Will (the deceased) wasn’t able to fully understand what they were doing when they created the Will. This means proving they didn’t understand the effects of the Will, what property they had, or who might expect to benefit from their estate.
Such a lack of capacity might have been caused by something like dementia, mental illness, or being under the influence of drugs or alcohol.
The legal test for whether someone had the mental capacity to make a Will comes from an old case called Banks v Goodfellow (1870). This case sets out four key things: the person must understand that they are making a Will and what the Will does; they must understand what property they have to leave behind; they need to know who might expect to benefit from their Will; and their mind should not be affected by any disorder that would change their decisions.
To prove incapacity, you will need evidence such as medical records, expert opinions from doctors or psychologists, and statements from people who knew the deceased. It’s also important to consider the timing of the Will - was it made when the person was already diagnosed or showing signs of mental decline?
To start the process, you must file a caveat with the Supreme Court of NSW to stop the Will from being probated (approved by the court). After that, you file a summons and an affidavit explaining why you believe the deceased lacked capacity. The executor and other interested parties will have the chance to respond.
If the court finds that the deceased did not have testamentary capacity, the Will may be declared invalid. If this happens, the estate will usually be distributed based on an earlier valid Will, or if there isn’t one, under the rules of intestacy (which means the estate is divided according to the law).
Contesting a Will on the grounds of incapacity can be complicated so it is important to get legal advice from the start. Your first step should be to contact our office to arrange a consultation. You can contact us by by phone or our 'Ask a Question' tool on our website.