The Diagnosis Isn’t the Case: Contesting a Will Signed During Dementia in California

by Michael A. Hackard

Publication Date April 27, 2026 in Will Contests

The Diagnosis Isn’t the Case: What California Families Must Understand Before Contesting a Will Signed During Dementia

Three adult children are sitting at a kitchen table in Sacramento. The oldest has driven four hours. The youngest flew in from out of state. Between them sits a will, their father’s last will and testament, signed eight weeks before he died, and none of them recognizes the document in front of them. The estate they expected, the one their father had described to them over decades of Thanksgiving dinners and quiet conversations, has been redirected almost entirely to a woman who moved into the house fourteen months ago as a paid caregiver. 

Their father was diagnosed with Alzheimer’s disease two years before he signed this document. They want to know whether that diagnosis voids the will. The honest answer, the one that actually helps them, is that the diagnosis is almost never the whole story, and understanding why is the first step toward knowing whether they have a case worth pursuing.

Testamentary capacity disputes involving dementia are among the most fact-intensive matters in California estate litigation. Families arrive with a reasonable assumption: if a person had dementia, then surely the will is invalid. California law does not work that way, and the gap between that assumption and the legal standard is where families either build a strong case or waste years pursuing the wrong theory. What courts actually examine is far more specific, far more demanding, and far more dependent on the particular circumstances of a particular day.

What California Law Actually Requires

Under California Probate Code § 6100.5, signing a will is not enough. The person making it has to actually understand what they are doing at the exact moment they sign.

The law requires four things to be present at the same time. They need to know they are creating a legal document that controls what happens to their property after death. They need to have a realistic picture of what they own. They need to recognize the people who would normally inherit from them. And they need to understand what their specific choices actually do.

If any one of those four things is missing in that moment, the will is legally invalid. It does not matter if an attorney drafted it, or witnesses were present. The paperwork does not fix the problem. Mental capacity at the time of signing is the requirement, and nothing substitutes for it.

The phrase “at the time of signing” carries enormous weight. California courts do not evaluate a testator’s general cognitive condition over a six-month period and then apply a grade to the will.

They reconstruct, as precisely as the available evidence allows, the testator’s mental state on the specific day and at the approximate hour the pen touched paper. Medical records from two months before the signing matter. Caregiver notes from the week of signing matter more. What the attorney who drafted the will observed during the signing ceremony matters most. This is a granular, day-specific inquiry that requires the kind of investigative work that general practitioners rarely anticipate when families first walk through the door.

The Lucid Interval Doctrine and Why It Cuts Both Ways

A dementia diagnosis does not automatically invalidate a will.

California law recognizes what is called a lucid interval. Even someone with a serious dementia diagnosis can experience periods of genuine mental clarity between episodes of confusion or disorientation. If they signed a will during one of those windows, California courts have consistently upheld that document as valid.

That is the part most families do not expect. They assume the diagnosis settles the question. It does not. What matters is the person’s mental state on the specific day they signed, not their condition the week before or the week after.

A will executed during a real lucid interval can hold up in court, even if the testator was severely impaired on either side of that date.

The doctrine cuts in the other direction as well, and this is the part that families on the other side of the table need to understand. A person who has never received a formal dementia diagnosis can still lack testamentary capacity on the day they sign a will. Acute delirium from a medication interaction, a urinary tract infection causing sudden cognitive disruption, a severe depressive episode, or a psychotic break can all temporarily eliminate a person’s ability to satisfy the four-element standard under § 6100.5.

The absence of a diagnosis is not a defense to a capacity challenge, and the presence of a diagnosis is not a guarantee of success. The diagnosis points investigators toward the right questions. It does not answer them.

Reading the Medical Record as a Legal Document

When Hackard Law takes on a potential will contest, the medical record is the first thing we ask for.

Alzheimer’s and related dementias do not just affect memory. They produce a specific set of behavioral and neuropsychiatric symptoms that carry direct legal weight. The Alzheimer’s Foundation of America has documented them: apathy, depression, irritability, agitation, aggression, psychosis, delusions, perceptual disturbances, and hallucinations.

These are not just clinical observations. When any of these symptoms appear in a chart close to the date a will was signed, they become evidence. A court can weigh each one against the four-part standard under § 6100.5.

The medical record does not just tell us how sick someone was. It tells us what was happening to their mind at the moment they signed.

A physician’s note from the week of signing, documenting that the testator was “patient confused about location and family members,” speaks directly to whether the testator understood who their natural heirs were. A nursing home record stating “patient unable to recall property holdings or financial accounts” indicates whether the testator understood the extent of their estate. These are not merely medical observations.

They are the raw material from which attorneys reconstruct the legal picture of a testator’s mind on a specific day, and experienced estate litigation counsel know exactly how to present that reconstruction to a probate court.

The Caregiver Pattern: When Capacity and Undue Influence Overlap

The scenario that opened this piece — the paid caregiver who appears in a dramatically altered will shortly after a dementia diagnosis- is not an unusual fact pattern. It is, in the experience of this firm, one of the most common. And it is significant because it raises two distinct legal theories simultaneously: testamentary capacity and undue influence.

Dementia does not just affect memory. It erodes independence.

As the condition advances, a person becomes increasingly reliant on whoever is physically present in their life. That dependence creates real vulnerability. And some people exploit it deliberately: caregivers, new romantic partners, recent acquaintances who insert themselves at the right moment.

California law accounts for this. When someone in a position of trust ends up with a disproportionate benefit under a will, especially one that looks nothing like what the testator had previously expressed, courts take a harder look at how that will came to exist.

The legal question shifts. It is no longer just whether the testator understood what they were signing. It is whether the decision to sign was actually theirs.

These two theories reinforce each other in litigation. Evidence that a testator lacked capacity on the day of signing supports the inference that they were susceptible to influence. Evidence of a controlling caregiver who isolated the testator from family members supports the inference that the testator’s apparent decisions were not truly their own.

Families who recognize this pattern should understand that caregiver financial exploitation and will contests are often two facets of the same underlying wrong, and that the legal remedies available address both.

What Evidence Courts Actually Consider

Reconstructing a testator’s mental state on a specific day requires assembling evidence from multiple sources. And the quality of that reconstruction depends heavily on how quickly the process begins.

Medical records are foundational, but they rarely tell the complete story. Caregiver logs and home health agency records often contain day-by-day behavioral observations that are more granular than anything a physician documents during a quarterly visit.

Communications between the testator and family members, such as text messages, emails, and voicemails, can reveal whether the testator was oriented and coherent, or confused and easily redirected, in the period surrounding the signing.

The attorney who drafted and supervised the execution of the will is a critical witness. California courts have held that an estate planning attorney’s observations of the testator during the signing ceremony are highly probative of capacity. If that attorney conducted no independent capacity screening, asked no probing questions, and simply presented documents for signature at the direction of the caregiver who arranged the appointment, that procedural failure is itself significant.

It raises the question of whether the attorney was serving the testator or the person who hired them. The hidden dangers of informal estate planning conversations and inadequate drafting practices are patterns that experienced litigators recognize quickly.

Witnesses to the signing ceremony, neighbors who regularly interacted with the testator, and former caregivers who left before the new will was executed can all provide testimony that fills in the picture. The goal is to give the probate court enough specific, contemporaneous evidence to evaluate what was actually happening in the testator’s mind on the day that matters.

The Timeline Problem: Why Delay Destroys Cases

Evidence in testamentary capacity cases is perishable. Witnesses move, forget, and die. Caregiver logs get discarded. Electronic communications get deleted. Medical providers archive and eventually destroy records.

The longer a family waits to consult an attorney after discovering a suspicious will, the narrower the evidentiary window becomes.

California’s statute of limitations for will contests is 120 days from the date the will is admitted to probate, or 60 days from the date notice is served on the contestant, whichever is later. Missing that deadline forecloses the contest entirely, regardless of how strong the underlying facts might be.

Beyond the formal deadline, there is a practical urgency that families often underestimate.

Assets can be distributed before a contest is filed. Property can be transferred, sold, or encumbered. Bank accounts can be emptied. The sooner counsel is engaged, the sooner protective measures, including requests for preliminary injunctions and asset freezes, can be put in place.

Families who wait six months to “see how things shake out” often discover that the estate they intended to contest has already been substantially dissipated. Understanding how long-term asset distribution takes and what can happen during that window is essential context for anyone considering a challenge.

What Families Should Do Right Now

If you are holding a will that does not reflect what your parent told you throughout their life, and if that parent had a dementia diagnosis at or near the time of signing, the first priority is documentation.

Gather every medical record you can access. Preserve any communications your parent sent or received in the months leading up to the signing. Identify every person who had regular contact with your parent during that period and write down their names and contact information before memories fade.

If you have reason to believe assets are being moved or dissipated, say so clearly when you speak with an attorney. That information affects both the urgency and the strategy.

The second priority is a candid evaluation of both theories, capacity, and undue influence, because the strongest cases often rest on both. Elder financial abuse in California carries its own statutory remedies, including the possibility of enhanced damages and attorney fee recovery, which can make litigation economically viable even when the estate itself is not enormous.

Families who understand the full range of available claims are better positioned to make informed decisions about whether and how to proceed.

If your family is facing a will that does not reflect what your loved one told you throughout their life, and if a dementia diagnosis was part of their final years, the path forward begins with an honest evaluation of the specific facts surrounding the day that document was signed. Hackard Law has spent decades investigating exactly those facts, in exactly these cases, across California. The evidence is out there. The question is whether you move quickly enough to find it.