Mental capacity to make a will.
When a person has a degenerative brain disease such as Alzheimer’s disease or dementia would it be too late for him or her to make a will? Well, it depends on whether the person has sufficient mental capacity to do so at the time of making the will.
In Australia, we are guided by the words of Judge Cockburn who is often quoted from the case of Banks v Goodfellow  where he explained in his judgement that it is essential to a person’s ability to make a will that the person:
“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 mind shall poison his affections, pervert his sense of right, or prevent the exercise of his natural faculties —that no insane delusions shall influence his will in disposing his property and bring about a disposal of it which, if the mind had been sound, would not have been made.”
Of course, a person with a severe degenerative brain disease unable to speak clearly or otherwise instruct a solicitor would present as having no mental capacity, an obvious inability to make a will. In those circumstances, the person will have left it too late to make a will or change their will.
Mental capacity is for a solicitor to assess when receiving instructions from a client and as you can see from Banks v Goodfellow, the test is not very difficult to pass where the person is functioning normally during a conversation about their will and is able to express his or her intentions. Over the years, I have found that a person with mild dementia has sufficient mental function to request a will, generally explain their assets and outline their desired dispositions to beneficiaries under his or her will. Often, one needs to be patient and allow the person adequate time to speak during such a conversation to ensure the right instructions are received for the will.
People assisting an older person need to be patient, allowing the will-maker the time they need to talk to the solicitor and only assist with information when asked to by the will-maker during a visit to the solicitor’s office.