16/07/2026
Ford Sumner Partner Jaesen Sumner recently acted for a temporary administrator in an estate matter before the High Court (Thyne v Public Trust and Ors 2026 NZHC – https://lnkd.in/eH7yVQFC) involving multiple competing wills and questions of testamentary capacity.
The case required the Court to determine which of several wills was valid. The deceased had executed three identical wills in October 2023, as well as earlier wills in 2023 and 2019. There were also defects in the ex*****on of certain wills, requiring consideration of section 31 of the Wills Act 2007.
A central issue was whether the deceased had testamentary capacity when signing the final wills in October 2023. This was contentious because the deceased had been diagnosed with mixed dementia in 2021, and his GP expressed the view that he likely lacked full capacity at the time of ex*****on.
Despite those concerns, the High Court found, on the balance of probabilities, that the deceased possessed testamentary capacity. In reaching that conclusion, the Court relied on:
● Evidence from witnesses who were present when the wills were executed;
● The consistency of the October 2023 wills with the deceased's earlier testamentary intentions; and
● The well-established principle that imperfect memory or cognitive decline does not necessarily equate to a lack of testamentary capacity.
The decision provides a practical and contemporary application of the enduring principles established in Banks v Goodfellow (1870) LR 5 QB 549.
Importantly, the judgment reinforces that testamentary capacity does not require perfect cognition. Rather, the testator must have a sufficient understanding of the nature and effect of making a will, the extent of their property, and the claims of those who might reasonably expect to benefit from the estate.
The case also illustrates that, even where there is medical evidence suggesting cognitive impairment, the Court may place significant weight on lay witness evidence demonstrating that the testator understood what they were doing at the time the will was executed.
The issues were brought before the Court through originating application, a departure from standard proceedings, allowing all questions about the will to be resolved efficiently and with everyone affected having an opportunity to be heard. Using procedures available under the Administration Act 1969, the High Court Rules and the Wills Act 2007, the Court was able to reduce the cost, delay and uncertainty often associated with estate disputes and help protect beneficiaries from unnecessary expense.
As New Zealand's population ages and dementia-related challenges become increasingly common in estate litigation, the decision serves as a timely reminder that testamentary capacity remains a practical, fact-specific inquiry focused on understanding rather than perfection.
