If a child receives less than their 'fair share' under their parent's will, the question is: Was the parent making a rational decision or was it a symptom of dementia?

In a recent legal case, the father's 2008 will left an estate valued at $3.2 million to his six daughters in equal shares (about $530,000 each). But in 2013, the father made a new will and left $40,000 to five of the daughters and $3 million to the sixth daughter. The father died in 2015 aged 85.

Not unnaturally, two of the daughters who were left $40,000 challenged the will. They argued that their father had lost the plot - that he lacked the mental capacity to assess what he had to leave in his will, and to decide upon the relative claims of his daughters.

They relied upon some sensational comments made by their father before he made the 2013 will, including:

  • He had seen prostitutes in the street ringing their bells at midnight
  • He had seen a black panther in the street
  • His wife was running a brothel making $5,000 per week
  • His bank had given him $100,000 for being a good customer

Despite these hallucinations, the medical evidence was that he suffered mild cognitive impairment, not dementia. The solicitor and a neighbour gave evidence that he was coherent and in command of his faculties with them, with no sign of dementia.

The NSW Court of Appeal concluded that the hallucinations were episodic and did not affect his mental capacity to make a will. The fact that he left the five daughters $40,000 each was a rational response to a family feud, where they had sided with their mother, while the sixth daughter who sided with her father received the bulk of his estate.

The conclusion is that it takes more than hallucinations and mild cognitive impairment to invalidate a will for which there is a rational explanation.