There can be no doubting the huge advances made in medical science and practice in the last 150 years. 

Allegations of a lack of capacity to make a valid will are now more prevalent than ever, thanks largely to the fact that older people now make up a bigger percentage of the population in almost all societies world-wide than ever before.

The obvious link between these 2 sentences is that medical science should devise a test applicable by the legal profession to determine the capacity of a person to draft a valid will. But the complexity of mental capacity and its accurate assessment continues to make such a test impractical it would seem.  

The result is that mental capacity to draft a will in Australia is still governed by a test formulated in the 1870 English case of Banks v Goodfellow.

In this case, which incidentally involved a testator suffering from psychosis, not dementia in any of its forms, the court formulated the will-making capacity as such:

The testator must understand

1. The nature and effect of the document being signed
2. The nature and extent of the assets involved
3. The people who may have “moral claims” on the estate
4. And must not be suffering from “a disorder of the mind that poisons the testator’s affections, perverts his sense of right or prevents the exercise of his natural faculties – that no insane delusion shall influence his will in disposing of his property and bring about a disposal of it which, if the mind had been sound, would not have been made”.

Practitioners tend to concentrate on the first 3 legs of this test, because the fourth defies application. Does the fourth leg describe dementia, and if so, which variety, at what stage and to what extent? Then also remember the testator is dead, so you can’t ask him/her!

Is it any wonder this is such a disputed area of practice?