When a family starts asking whether a loved one “really knew what they were signing,” the dispute often turns into a capacity case. These contests can be emotional, fact-heavy, and highly time-sensitive. They also tend to overlap with concerns about dementia, medication effects, caregiver pressure, and sudden last-minute changes to an estate plan.
The tricky part is that capacity is not the same as diagnosis. A person may have Alzheimer’s disease, mild cognitive impairment, or episodes of confusion and still have legal capacity at the relevant moment. On the other hand, a person with no formal diagnosis may still lack the mental ability required to sign a will or amend a trust. That is one reason these cases often rise or fall on details: timing, medical records, witness observations, and the exact document that was signed.
In this post you’ll learn how capacity issues are evaluated in a will or trust contest, what evidence tends to matter most, how capacity differs between wills and trusts, and why families often benefit from speaking with counsel early while records and witness memories are still available.
<aside> 💡 Scroll to the bottom for every post in this series.
</aside>
Capacity disputes sit at the center of many estate fights because a valid will or trust depends on the person signing it understanding what they were doing in a legally meaningful way. The American Bar Association describes testamentary capacity in terms of whether the person could appreciate the nature of making a will, the nature and extent of their property, the people who would naturally receive their bounty, and the overall distribution plan laid out in the document (ABA).
That framework sounds straightforward, but the real-world facts are rarely clean. Families may be looking at a loved one who had memory loss, hospitalizations, psychiatric symptoms, or increasing dependence on a caregiver. In 2025, the Alzheimer’s Association estimated that 7.2 million Americans age 65 and older were living with Alzheimer’s dementia, with prevalence increasing sharply by age (Alzheimer’s Association). As the population ages, more estates are likely to involve some level of cognitive decline, which helps explain why capacity challenges remain such a major issue in probate and trust litigation.
If you want a deeper overview of the legal building blocks behind these claims, our related guide on how courts look at mental decline, cognitive impairment, and testamentary intent gives broader background that pairs closely with this topic.
In general terms, a will contest focuses on testamentary capacity. Many states use a similar core test, even though wording can vary by jurisdiction. Courts often ask whether, at the time the will was executed, the testator could:
That legal standard is often narrower than families expect. A person does not necessarily lose testamentary capacity simply because they were elderly, forgetful, eccentric, depressed, or diagnosed with dementia. The legal question is usually tied to the moment of execution, not whether the person seemed impaired in a broad everyday sense. The ABA’s probate update in 2025 highlighted a Maine case, Estate of Spofford, where a will challenge failed despite dementia and Alzheimer’s diagnoses because there was substantial evidence the testator had capacity on the day of execution, including video of the signing and testimony from the primary care physician (ABA Probate Update).
That is one reason families are often surprised by these cases. A diagnosis may matter, but diagnosis alone does not usually decide the dispute.
Trust disputes can be more complicated because the legal standard may depend on the kind of trust and the state law involved. Under Section 601 of the Uniform Trust Code, the capacity required to create, amend, revoke, or direct the trustee of a revocable trust is the same as that required to make a will (Uniform Law Commission). The comments explain that revocable trusts are commonly used as will substitutes, so the law often treats the capacity standard similarly.
That said, not every state follows the same exact route in every context, and an irrevocable trust or lifetime transfer can trigger a different capacity analysis. This is one area where state-specific law matters a great deal. A trust contest may also involve additional questions, such as whether the amendment method in the trust document was followed, whether an agent acted under a power of attorney, or whether the settlor was subject to undue influence at the same time.