Disclaimer: This article is for general informational purposes only and is not legal advice. For advice about a specific situation, consult a Missouri probate lawyer.
Short answer
To challenge a will in Missouri on the basis that the testator lacked testamentary capacity or was subject to undue influence, you need documentary, testimonial, and—sometimes—expert evidence that together show the necessary elements. Medical records, witness statements about the testator’s mental state and the signing events, communications showing pressure or control, financial records, and expert opinions are commonly used. Missouri law governing wills is in the Missouri Revised Statutes, Chapter 474 (Wills): https://revisor.mo.gov/main/Chapter.aspx?chapter=474.
Detailed answer — How Missouri treats capacity and undue influence
Testamentary capacity (general legal standard)
Missouri follows the traditional common-law standard for testamentary capacity. At the time the will was signed, the person (the testator) must generally have had sufficient mental capacity to:
- Understand the nature and effect of making a will (that they were disposing of property by a written instrument);
- Know the nature and extent of their property as a whole to the extent that they have knowledge;
- Recognize the natural objects of their bounty (close family or others who would expect to inherit); and
- Hold these facts in mind long enough to form a rational plan for distributing property and to express that intent in the will.
Evidence showing inability to meet these elements can support a capacity challenge. The Missouri statutes that govern will execution formalities are in Chapter 474: https://revisor.mo.gov/main/Chapter.aspx?chapter=474.
Undue influence (general legal standard)
Undue influence occurs when someone exerts pressure or control over the testator so that the resulting will reflects the influencer’s desires rather than the testator’s free will. Courts look for proof that the influencer:
- Had opportunity to exercise control over the testator;
- Had a confidential or dominant relationship with the testator (not every close relationship is confidential, but caregiving, fiduciary, or heavy dependence can be evidence);
- Acted in a way that procured the will (isolating the testator, controlling access to lawyers or witnesses, coaching testimony, handling the paperwork); and
- Benefitted from the will in a way that is suspicious or inconsistent with earlier testamentary plans.
Missouri courts evaluate the totality of the circumstances. A presumption of undue influence may arise in suspicious situations (for example, when an entirely unexpected beneficiary receives a large gift and the alleged influencer had a dominant role), shifting the burden to the proponent of the will to rebut the presumption with evidence of independent advice, fair dealing, or the testator’s informed choice.
Types of evidence that commonly prove lack of capacity
- Medical records: Hospital and clinic records showing dementia, delirium, stroke, severe psychiatric illness, medication effects, or cognitive testing near the time the will was executed.
- Physician testimony or expert opinion: Doctors or neuropsychologists who treated or evaluated the testator can explain whether the testator met the capacity elements at signing.
- Witness testimony about the signing event: Attesting witnesses (if available), family members, caregivers, or the attorney who drafted the will can describe the testator’s awareness, confusion, or inability to understand what they were signing.
- Prior statements and writings: Letters, emails, recorded conversations, or earlier wills that show different testamentary intent or demonstrate cognitive decline (e.g., incoherent notes, missed appointments).
- Handwriting or signature analysis: For late-stage dementia challenges, forensic handwriting experts can show tremor or change in signature quality.
- Medication lists and treatment notes: Evidence that sedating or mind-altering drugs were prescribed or administered around the signing.
Types of evidence that commonly prove undue influence
- Evidence of a confidential/dominant relationship: Documentation that the beneficiary controlled the testator’s finances, medical appointments, household access, or legal affairs.
- Opportunity and isolation: Records or testimony showing the influencer arranged private meetings with the testator, excluded family, or prevented independent advice.
- Benefit and suspicious circumstances: A markedly different distribution in the contested will compared with prior wills, especially if the new beneficiary gained significantly and the change appears to lack rational explanation.
- Communications and directives: Texts, emails, voice messages, or contemporaneous notes showing pressure, threats, coercion, or coaching to sign the document.
- Conduct after the will: Actions such as hiding the will, destroying older wills, paying for the will’s preparation, or restricting access to the testator immediately before signing.
- Witness accounts: Attesting witnesses, the drafting attorney, or others who can say whether the testator was acting freely or appeared coached or fearful.
Burden and standard of proof
A person contesting a will in Missouri bears the burden to prove lack of capacity or undue influence. Courts typically require convincing evidence given the strong public policy favoring the validity of properly executed wills. In many cases the court requires clear and convincing evidence to set aside a will; the presence of suspicious circumstances can create a presumption that shifts evidentiary burdens. Consult a Missouri probate lawyer early so pleadings and evidence are gathered quickly.
Practical steps to build a contest or to defend a will
- Immediately collect medical records and medication logs from the period around the will’s execution.
- Secure witness names and written statements from anyone present at or involved in the signing.
- Preserve electronic evidence: texts, emails, recordings, appointment logs, bank records, and caregiving schedules.
- Ask a qualified attorney to obtain subpoenas and disclosure in probate court before records are lost or destroyed.
- Consider expert evaluations (medical or forensic) to explain cognitive status or to analyze suspicious behavior patterns.
- If you are planning a will and want to reduce later contest risk: use an independent attorney, a clear execution ceremony with impartial witnesses, document the testator’s capacity (physician letter or cognitive testing when appropriate), and avoid appearances of coercion.
Timing and procedure
Missouri has specific probate procedures and timelines for will contests. An interested person who believes undue influence or incapacity occurred should act promptly after the will is offered for probate. Key procedural rules and timelines appear in Missouri probate law; see the courts’ probate information and Chapter 474 of the Revised Statutes: https://revisor.mo.gov/main/Chapter.aspx?chapter=474 and https://www.courts.mo.gov/page.jsp?id=461.
When to consult a lawyer
Challenging or defending a will often involves tight deadlines, evidentiary rules, and complex factual proof. Contact a Missouri probate lawyer quickly to preserve evidence, understand deadlines, and evaluate the strength of the available proof.
Helpful Hints
- Start gathering records immediately — medical and digital evidence can disappear quickly.
- Get written statements from witnesses while memories are fresh.
- Look for patterns: sudden changes in beneficiaries, secrecy, or new caregivers are red flags.
- If possible, obtain contemporaneous medical assessments around the signing date.
- Preserve bank and transfer records to show unusual financial activity.
- Consult a probate lawyer in Missouri early to make sure evidence is collected and the claim is filed on time.
Relevant Missouri law: Missouri Revised Statutes, Chapter 474 (Wills): https://revisor.mo.gov/main/Chapter.aspx?chapter=474. For general probate and local court procedures see Missouri Courts — Probate: https://www.courts.mo.gov/page.jsp?id=461.
Remember: This is general information only and does not create an attorney-client relationship or substitute for legal advice tailored to your situation. For specific guidance, contact a Missouri probate lawyer.