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Lack of Capacity Trust Contest California: Proving Mental Incapacity

Rozsa GyeneNovember 1, 202512 min read

Lack of Capacity Trust Contest California: Proving Mental Incapacity

Lack of testamentary capacity is the most common ground for contesting a trust in California. When someone creates or modifies a trust while mentally incapacitated, those documents are invalid. However, proving lack of capacity requires understanding California's legal standard, gathering compelling medical evidence, and often battling the presumption that adults are competent.

This guide covers everything you need to know about capacity challenges in California trust litigation.

California Capacity Standard

The Legal Test (Probate Code ยง811)

To have testamentary capacity in California, the settlor must be able to:

  1. Understand the nature of the testamentary act - Know they're creating/changing a trust
  2. Understand and recollect the nature and situation of their property - Know what they own
  3. Remember and understand their relations to living descendants, spouse, parents, and those whose interests are affected - Know their family
  4. Understand the practical effect and significance of the trust provisions - Comprehend what the trust does

All four elements required - Failure of any one means incapacity.

When Capacity Is Measured

Critical moment: Capacity assessed at the exact time trust was executed

Not:

  • General capacity over months/years
  • Capacity on other days
  • Current capacity (if challenging old trust)

Lucid intervals: Even if person generally incapacitated, trust valid if executed during "lucid interval" of capacity.

Presumption of Capacity

California law presumes all adults have capacity

Burden on contestant to prove incapacity by clear and convincing evidence

This makes capacity challenges difficult - presumption favors validity.

Medical Conditions Affecting Capacity

Dementia

Most common capacity issue

Types:

  • Alzheimer's disease (60-80% of dementia)
  • Vascular dementia
  • Lewy body dementia
  • Frontotemporal dementia
  • Mixed dementia

Progression:

  • Early stage: Mild memory loss, some confusion
  • Middle stage: Significant memory loss, confusion, poor judgment
  • Late stage: Severe cognitive decline, cannot recognize family

Trust executed in middle-late stage likely invalid

Alzheimer's Disease

Progressive brain disease destroying memory and thinking skills

Symptoms affecting capacity:

  • Memory loss
  • Confusion about time/place
  • Difficulty with familiar tasks
  • Poor judgment
  • Personality changes
  • Cannot follow complex instructions

Timeline matters:

  • How long since diagnosis?
  • What stage at trust execution?
  • Medical records showing progression?

Delirium

Temporary confused state often caused by:

  • Medications
  • Infections (UTI common in elderly)
  • Hospitalization
  • Surgery/anesthesia
  • Dehydration

Can cause temporary incapacity

Example: Elderly person signs trust while hospitalized with UTI-induced delirium = Potentially invalid

Mental Illness

Conditions that may affect capacity:

  • Severe depression with psychotic features
  • Bipolar disorder (manic phase)
  • Schizophrenia
  • Paranoid delusions

Must show condition actually impaired testamentary capacity

Stroke

Can cause:

  • Cognitive impairment
  • Aphasia (communication problems)
  • Memory issues
  • Executive function deficits

Recent stroke at time of trust execution raises capacity questions.

Medications

Drugs that can impair capacity:

  • Opioid pain medications
  • Benzodiazepines (Valium, Xanax)
  • Sleep medications (Ambien)
  • Certain antipsychotics
  • Heavy sedation

Must show:

  • What medications taken
  • Dosage
  • Timing relative to trust execution
  • Known cognitive side effects

Evidence of Incapacity

Medical Records

Most important evidence

Key medical documents:

  • Diagnosis of dementia, Alzheimer's, etc.
  • Doctor's notes describing cognitive state
  • Mini-Mental State Exam (MMSE) scores (0-30 scale, <24 suggests impairment)
  • Montreal Cognitive Assessment (MoCA) scores
  • Neuropsychological testing results
  • Brain imaging (CT, MRI) showing atrophy
  • Hospital records if trust executed during hospitalization
  • Medication lists and prescribing information

Timeline crucial: Records closest to trust execution date most valuable.

Lay Witness Testimony

Family, friends, caregivers can testify about:

  • Confusion and disorientation
  • Memory loss (repeating questions, forgetting conversations)
  • Not recognizing family members
  • Getting lost in familiar places
  • Inability to manage finances
  • Personality changes
  • Decline in hygiene/self-care
  • Difficulty with daily tasks

Specific examples better than general statements

Example - Strong testimony: "On the day Mom signed the trust, she asked me three times who I was and thought it was 1985."

Example - Weak testimony: "Mom seemed a bit confused sometimes."

The Attorney's Testimony

Attorney who prepared trust is critical witness

Attorney will testify about:

  • Settlor's appearance and demeanor
  • Conversation about trust purposes
  • Questions settlor asked
  • Whether settlor understood provisions
  • Any concerns about capacity
  • Steps taken to assess capacity

Problem: Attorney almost always testifies settlor seemed competent (protects attorney from malpractice).

Expert Testimony

Forensic psychiatrist or neuropsychologist reviews:

  • Medical records
  • Witness statements
  • Deposition testimony
  • Trust documents

Expert opines:

  • Whether settlor had capacity
  • How medical condition affected cognitive function
  • Whether condition would impair testamentary capacity
  • Consistency with described symptoms

Expert costs: $15,000-$50,000+

Essential in most capacity cases

Common Capacity Scenarios

Scenario 1: Progressive Dementia

Facts:

  • 2015: Dementia diagnosis
  • 2018: MMSE score 18/30 (moderate impairment)
  • 2020: MMSE score 12/30 (severe impairment)
  • 2020: Trust executed changing beneficiaries
  • Family reports severe confusion by 2020

Analysis: Strong capacity challenge - medical progression documented, severe impairment at execution.

Scenario 2: Lucid Interval

Facts:

  • Advanced dementia diagnosis
  • Generally confused and disoriented
  • Attorney testifies settlor was clear and coherent at signing
  • Trust provisions make logical sense
  • No medical records from exact date

Analysis: Difficult case - Lucid interval defense available. Need strong lay testimony about confusion that same day.

Scenario 3: Hospitalization

Facts:

  • Trust signed in hospital
  • Post-surgical, on pain medications
  • Hospital records show disorientation
  • Family wasn't notified of signing
  • Rushed execution

Analysis: Good capacity challenge - hospitalization, medications, disorientation documented.

Scenario 4: Mild Cognitive Impairment

Facts:

  • MCI diagnosis (not dementia)
  • MMSE score 24/30 (borderline)
  • Mostly independent
  • Some memory issues
  • Trust provisions logical

Analysis: Weak capacity case - MCI alone usually insufficient. Need more evidence of impairment affecting testamentary capacity.

Defending Against Capacity Challenge

Proponent's Arguments

Defense strategies:

1. Presumption of capacity

  • Contestant must overcome presumption
  • Unless clearly proven, capacity presumed

2. Attorney testimony

  • Attorney who prepared trust testifies settlor was competent
  • Attorney would have noticed incapacity
  • Attorney asked appropriate questions

3. Rational trust provisions

  • Trust makes logical sense
  • Provisions consistent with relationships
  • No bizarre or irrational dispositions

4. Lucid interval

  • Even if generally impaired, competent when executed
  • Witnesses testify to clarity that day

5. Medical evidence insufficient

  • Diagnosis doesn't equal incapacity
  • Records not from date of execution
  • Experts disagree

Rebutting Defense

Contestant responses:

Re: presumption

  • Present overwhelming evidence
  • Medical records, multiple witnesses
  • Expert testimony

Re: attorney testimony

  • Attorney not medical expert
  • Brief meeting insufficient to assess
  • Attorney has bias (avoids malpractice)

Re: rational provisions

  • Undue influence can coexist with incapacity
  • Provisions favor person controlling settlor

Re: lucid interval

  • Medical records show no lucid periods
  • Witnesses testify to confusion that day
  • No medical documentation of lucidity

Capacity vs. Undue Influence

Key Differences

Capacity:

  • Medical/psychological condition
  • Settlor couldn't understand

Undue influence:

  • External pressure
  • Settlor could understand but will overpowered

Often alleged together:

  • Vulnerability from incapacity
  • Made susceptible to influence

Stronger case when both alleged with supporting evidence.

Procedural Issues

Statute of Limitations

120 days from receiving notice trust became irrevocable

Same as other trust contests - act quickly

Burden of Proof

Contestant must prove incapacity by clear and convincing evidence

High standard - more than "preponderance" (more likely than not)

Must be "highly probable" settlor lacked capacity

Discovery

Critical discovery:

  • All medical records from years before and including execution date
  • Attorney's file from trust preparation
  • Depositions of attorney, doctors, family, witnesses
  • Expert depositions

Medical records often under HIPAA

  • Need proper authorization
  • Subpoena if necessary
  • May need court order

Settlement Considerations

When to Settle

Consider settlement if:

  • Medical evidence mixed
  • Attorney testimony strong for capacity
  • Lucid interval defensible
  • Costly expert battle ahead
  • Want to preserve family relationships

Settlement Structures

Common resolutions:

  • Modify trust to compromise
  • Contestant receives more than contested trust provides
  • Less than full victory but avoids trial risk

Example:

  • Contested trust: Daughter gets $50,000
  • Prior trust: Daughter got 50% ($500,000)
  • Settlement: Daughter receives $250,000
  • Avoids trial, both sides compromise

Costs

Attorney Fees

Typical costs:

  • Through trial: $75,000-$200,000
  • With appeals: $150,000-$350,000

Expert Costs

  • Forensic psychiatrist: $20,000-$50,000
  • Neuropsychologist: $15,000-$40,000
  • Medical records review: $5,000-$15,000

Total Investment

Complete capacity litigation: $100,000-$300,000+

Cost-benefit analysis essential

Key Takeaways

To prove lack of capacity:

  • Clear medical evidence of cognitive impairment
  • Records close to execution date
  • Multiple witnesses to confusion
  • Expert testimony
  • Evidence condition affected testamentary capacity specifically

Challenges:

  • Presumption of capacity
  • Attorney testimony for proponent
  • Lucid interval defense
  • High burden of proof
  • Expensive litigation

Best cases have:

  • Dementia/Alzheimer's diagnosis before execution
  • Medical records showing severe impairment
  • MMSE/MoCA scores showing cognitive decline
  • Multiple family witnesses
  • Irrational or suspicious trust provisions
  • Strong expert testimony

Related Articles

Learn more about trust litigation:

Frequently Asked Questions

What is the legal standard for testamentary capacity in California?

California requires that the settlor understand the nature of creating a trust, understand and recall their property, remember their family relationships and affected parties, and comprehend the practical effect of the trust provisions. All four elements are required, and failure of any one means the settlor lacked capacity. Capacity is assessed at the exact moment the trust was executed, not generally over time.

Can someone with dementia or Alzheimer's create a valid trust?

It depends on the stage and severity of the condition at the time the trust was executed. Early-stage dementia may not prevent someone from having testamentary capacity, while middle to late-stage dementia typically does. The key is whether the person could understand the four elements of capacity at the specific moment of execution. Medical records showing cognitive scores, doctor's notes, and progression timeline are critical evidence.

What is a lucid interval and how does it affect capacity challenges?

A lucid interval is a temporary period of mental clarity during which a person who is generally incapacitated has sufficient capacity to execute legal documents. Even if someone has advanced dementia, a trust executed during a lucid interval is valid. However, the burden is on the proponent to prove a lucid interval existed at the exact time of execution, typically through attorney testimony, witness statements, and the rationality of the trust provisions.

What evidence is needed to prove lack of capacity?

The strongest evidence includes medical records showing dementia or Alzheimer's diagnosis, cognitive test scores like MMSE or MoCA showing impairment, doctor's notes describing cognitive decline, brain imaging showing atrophy, and medications affecting cognition. Lay witness testimony from family and caregivers about specific examples of confusion is also valuable. Expert testimony from a forensic psychiatrist or neuropsychologist reviewing all evidence is typically essential to winning a capacity challenge.

How much does it cost to contest a trust based on lack of capacity?

A complete capacity challenge typically costs between $100,000 and $300,000 or more, including attorney fees of $75,000 to $200,000 through trial and expert costs of $20,000 to $50,000 for forensic psychiatrists and neuropsychologists. The high costs make a thorough cost-benefit analysis essential before filing. Consider what you stand to gain versus what you'll lose if unsuccessful, and ensure you have strong medical evidence supporting probable cause.

Need Help With a Capacity Challenge?

If you believe a trust was created or modified when the settlor lacked mental capacity, our experienced trust litigation attorneys can evaluate your medical evidence and advise on the strength of your case.

Contact us for a confidential consultation about your lack of capacity claim.

This article is for informational purposes only and does not constitute legal or medical advice. Capacity challenges are highly fact-specific and require expert evaluation. Consult with qualified legal and medical professionals about your specific situation.


Tags:#lack of capacity#mental capacity#trust contest#dementia#Alzheimer's
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Written by Rozsa Gyene, Esq.
California State Bar #208356 | 25+ Years Probate & Estate Experience
Last Updated: November 28, 2025

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