By Kenneth “Kenny” Sumner Jr.
In Texas, a will is only valid if the person who signed it was “of sound mind” at the moment they signed — what the law calls testamentary capacity. A lack of testamentary capacity means the signer didn’t understand what they owned, who their family was, or what the will actually did when they put pen to paper. Here’s the part that trips most families up: capacity is judged at one single moment, the instant the will was signed. A parent with advanced dementia can sign a perfectly valid will during a lucid stretch, and a parent with no diagnosis at all can lack capacity on a bad afternoon. That’s why these cases are rarely won or lost on a medical chart alone. More often, they’re decided by the handful of people who were actually in the room.
The short version
Texas law lets any person “of sound mind” make a will (Tex. Est. Code § 251.001). Sounds simple, but “sound mind” has a specific legal meaning the courts have used for well over a century. To have testamentary capacity, the person signing the will (the testator) had to be able to:
A will can also fail if the testator was acting under an “insane delusion” — a false, unshakable belief that drove how they gave away their property (for example, a fixed, baseless conviction that a loving child had betrayed them, written into the will). That standard comes straight from the Texas Supreme Court’s decision in Prather v. McClelland, 76 Tex. 574, 13 S.W. 543 (1890), and Texas courts still apply it today.
Notice what’s not on the list. The testator didn’t have to be sharp, healthy, organized, or even particularly pleasant. The law asks whether they could understand — not whether they made the choice you would have made.
No. This is the single biggest misconception we see, and it cuts both ways.
Texas measures capacity at one moment: the moment the will was signed. The Texas Supreme Court made this explicit in Croucher v. Croucher, 660 S.W.2d 55 (Tex. 1983). Evidence that someone was confused or incompetent at other times only matters if that condition was ongoing and there’s a real probability it was the same on the day of signing. A diagnosis from three months earlier doesn’t answer the question by itself. The day in the room does.
That’s where the lucid interval comes in. Capacity can flicker. Someone with a degenerative condition can be lost in the morning and clear by lunch. Texas law accepts that a person can sign a valid will during one of those clear stretches, even with a diagnosis on file. So a dementia diagnosis doesn’t automatically void a will, and the absence of one doesn’t save it. Each side is really fighting over the same narrow question: what was this person’s mind doing in the minutes they signed?
No, and this surprises people. The capacity to make a will is a lower bar than the capacity to sign a contract, run a business, or even validly grant a power of attorney. Someone who can no longer balance a checkbook or manage their own investments may still have enough understanding to make a valid will.
| Capacity to make a will | Capacity to sign a contract / POA | |
|---|---|---|
| What’s required | Understand, in general, your property, your family, and what the will does | A higher, more demanding level of understanding and judgment |
| When it’s measured | The single moment of signing | The moment of the transaction |
| Practical effect | A person in decline can still make a valid will in a lucid moment | The same person may lack capacity to manage assets or contract |
This is exactly why families get blindsided. A relative had a financial guardian, so the family assumes the will must be invalid too. Not necessarily. The questions are different, the standards are different, and the answers can be different.
Because medical records almost never capture the moment that matters.
A chart tells you what a doctor observed at an appointment, days or weeks before or after the signing. It shows the overall trajectory of someone’s decline, which is genuinely useful. But it usually can’t tell you whether, on the afternoon the will was signed, the testator was alert, answered questions sensibly, knew who their children were, and understood what they were signing. Records are a timeline. A will contest turns on a single point on that timeline. (We go deeper on this in our post on medical evidence in will contests.)
Medical evidence builds the backdrop. It rarely closes the case on its own.
Usually, the people in the room. If capacity comes down to one moment, then the most powerful evidence comes from the people who witnessed that moment, and in our experience this is the most under-investigated part of most will contests.
Under Texas law, a typed will is signed in front of two attesting witnesses, and a self-proving will is also signed before a notary. Often the drafting attorney is there too, supervising. Those three or four people saw exactly what a medical record can’t show:
This is where cases are actually won and lost, and where good lawyering matters most. Years later, those witnesses have to be tracked down. Notary records and journals can be requested. Depositions have to be built to lock in what each person actually remembers and to test it against the medical timeline and against each other. A witness who breezily signs “everything seemed fine” can look very different once you walk them through what the records show about that week.
We’ve covered who these witnesses are and why they matter in our companion post, why witnesses are crucial in contesting a will, and we walk through the proof a capacity case actually turns on in Was She Out of Her Mind? Proving Lack of Testamentary Capacity in Texas. The point here is narrower and more practical: in a capacity fight, the signing room is the battlefield. Build your case there.
These two get blurred constantly, and they’re not the same thing.
| Lack of testamentary capacity | Undue influence | |
|---|---|---|
| The core idea | The testator’s own mind couldn’t meet the standard | The testator’s mind was overpowered by someone else |
| The villain | A condition (dementia, delusion, illness) | A person (a caregiver, a new spouse, a controlling child) |
| What you prove | They didn’t understand what they were doing | Someone substituted their will for the testator’s |
They often get raised together in the same contest, because the same facts (an isolated, declining parent and a relative who suddenly controls everything) can point to both. But they’re separate legal grounds with separate proof. For the full menu of ways a Texas will can be challenged, see our overview of the grounds for contesting a will in Texas.
Generally, two years from the date the will is admitted to probate (Tex. Est. Code § 256.204). There are narrow exceptions (for fraud or forgery, and for a person who was legally incapacitated), but you should never plan around them. The bigger risk isn’t the calendar. It’s the evidence.
Memories fade. Witnesses move, and some pass away. Notary records get discarded. The clearest proof of what happened in that room is most recoverable right now and gets harder to find with every month that passes. If you suspect a capacity problem, the smartest first move is to preserve evidence early, not to wait until you’ve made up your mind to fight. (More on the clock here: how long you have to contest a will in Texas.)
Not sure when the will was admitted, or how much time is left? A short, free call will tell you where you stand. Call (281) 242-0995.
Capacity cases sit right where our two practices meet. Our attorneys handle will contests in the Fort Bend County courts and the Harris County statutory probate courts, and we also serve as court-appointed guardians ad litem in guardianship and probate matters in those same courts. That means we’ve watched the capacity question from both sides of the bench: as the lawyers proving a testator wasn’t of sound mind, and as the neutral charged with protecting someone whose capacity was in doubt. Partner Paul Romano is Board Certified in Estate Planning and Probate Law by the Texas Board of Legal Specialization, and our estate-litigation team — Paul Romano, Kenneth “Kenny” Sumner Jr., and Nicholas “Nick” Noe — has spent years inside these specific courts.
What that looks like in practice: we move fast to lock down the medical timeline, find and depose the witnesses and notary who were in the room, run down notary records before they disappear, and build the case around the one moment Texas law actually cares about.
If you think a loved one’s will doesn’t reflect a sound mind, or you’re defending a will and need to show it does, call us at (281) 242-0995 for a free consultation. We’ll tell you honestly what your case looks like and what it would take to pursue it.
Yes, potentially. A dementia diagnosis does not automatically invalidate a will in Texas. Capacity is measured at the moment of signing, and a person with dementia can sign a valid will during a lucid interval if they understood what they owned, who their family was, and what the will did.
It depends on timing. Once a Texas will has already been admitted to probate, the person challenging it generally carries the burden of proving the lack of capacity. If the will is challenged before it’s admitted, the person offering the will has to prove the testator had capacity (Croucher v. Croucher, 660 S.W.2d 55 (Tex. 1983)).
The most important evidence usually comes from the people present at the signing — the attesting witnesses, the notary, and the drafting attorney — along with medical records, testimony from family and caregivers, and sometimes a physician’s expert opinion. Because capacity is judged at the moment of signing, eyewitness testimony about that moment often outweighs records from other dates.
Generally, two years from the date the will is admitted to probate, with narrow exceptions for fraud, forgery, and legal incapacity (Tex. Est. Code § 256.204). Evidence is easiest to preserve early, so it’s wise to talk to a lawyer well before the deadline.
This article is for general informational purposes only and is not legal advice. Reading it does not create an attorney-client relationship. Every situation is different — for advice about your circumstances, speak with a qualified Texas attorney.