Can someone with dementia sign a valid will?

What testamentary capacity requires

A commonly used Florida definition of testamentary competence is the ability to understand generally the nature and extent of one's property, the natural objects of one's bounty and the practical effect of a will document.

Practitioners in New York describe capacity as requiring the testator to know the document is a will governing disposition of the estate and to have general awareness of assets, property holdings and accounts. They describe it as a significantly lower standard than for other transactions.

Timing and lucid intervals

Practitioners say New York courts assess testamentary capacity at signing, and that a will may remain valid if signed during a lucid interval despite dementia or intermittent confusion.

Another author says that if someone regains capacity, even temporarily, when signing a will, the court will admit the will to probate.

Proof in a contest

A North Carolina author says a mere showing of poor physical health or mental decline, or some signs of dementia, is not enough standing alone to show lack of testamentary capacity.

Practitioners describe California Probate Code section 810 as creating a rebuttable presumption that all persons have capacity. They say that even with an adverse diagnosis such as dementia, the contestant has an uphill climb under the burden of proof.

A practitioner says capacity assessments are heavily fact dependent and usually need expert medical opinion that goes past a diagnosis to functional impairment.