To make a valid will, you need a certain level of mental capacity. However, as a High Court ruling showed, a flawless memory is not required and those suffering from mild cognitive impairment may not be disqualified from expressing their wishes.

The case concerned a woman who was suffering from advanced vascular dementia when she died at the age of 90. She had, six years previously, made a will by which she left her entire estate to her son and only child.

He died before her, however, so that, under the terms of the will, her estate passed to one of her nephews and his wife. The will was the source of much antipathy within the family and one of the woman's nieces mounted a challenge to its validity on the basis that she lacked the mental capacity required to make it.

Ruling on the matter, the Court noted that the capacity to make a valid will depends on the potential to understand and is not to be equated with a test of memory. The legal test for capacity is not pitched so high as to prevent the elderly and others with imperfect memories from making a will.

The first indication that the woman was having mental health difficulties occurred about four months before she made the will. She was visited at home by a mental health nurse who noted her sadness that so many old friends had passed away. Such a lament, the Court noted, was not unusual for elderly people.

In his report, the nurse described her as a pleasant and sociable lady who stated that she had not left her home for over a year. Her short-term memory was impaired, she was disorientated as to time and she had occasional episodes of confusion. Overall, the nurse's opinion was that she was suffering from mild cognitive impairment.

Upholding the will's validity, the Court noted that it was rational on its face. Drafted by an experienced lawyer, its terms were simple and readily understandable. In the light of medical records, the likelihood was that she was still in the early stages of mental decline when she signed the document. She recollected the extent of her property, which largely consisted of her home, and was able to understand the nature of the will and its effect.