A will is one of the most important legal documents you can create — but not all wills hold up in court. Whether you’re drafting one for yourself or reviewing a loved one’s estate plan, it’s crucial to understand what can invalidate a will and how to avoid those mistakes.

In this guide, we’ll walk through the most common legal triggers that can make a will invalid, explain how courts evaluate contested wills, and help you ensure your estate plan stands up under scrutiny.

What Does It Mean to Invalidate a Will?

When a court invalidates a will, it declares the document legally unenforceable. This means the instructions left by the person who passed away (the testator) are not followed. Instead, the estate may be distributed according to state intestacy laws — as if no will existed at all.

This can completely change who inherits property and assets, create family disputes, and delay the probate process significantly.

1. Lack of Testamentary Capacity

To create a valid will, the testator must have “testamentary capacity,” which means they:

• Understand the nature of making a will
• Know the extent of their property
• Recognize their close family and potential heirs
• Understand how their will distributes their assets

If someone creates or amends a will while suffering from dementia, severe mental illness, or intoxication, the document may be challenged — and possibly invalidated.

Courts often rely on medical records, witness statements, and expert testimony when deciding whether the testator had sufficient mental capacity at the time the will was signed.

2. Undue Influence

Undue influence occurs when someone pressures, manipulates, or coerces the testator into changing their will in a way that benefits the influencer — often at the expense of others.

This may happen when:

• A caregiver isolates the testator from family
• A relative pressures the testator to disinherit someone
• Someone arranges for a new will to be signed under suspicious circumstances

Unlike fraud, undue influence involves emotional or psychological manipulation, not lies. Courts look for red flags like drastic changes in beneficiaries or the presence of the influencer during the will’s execution.

3. Improper Execution

Each state has its own rules for signing and witnessing a will. Check this FindLaw guide on will-making requirements for more details Failing to meet these requirements is one of the most common reasons wills get thrown out.

Typical requirements include:

• The testator must sign the will in front of at least two witnesses
• Witnesses must be legally competent adults
• In some states, notarization is required for a self-proving affidavit
• Witnesses cannot be beneficiaries (in many jurisdictions)

A will written on a napkin, signed privately, or witnessed by a person who stands to benefit may be considered invalid in court.

4. Fraud or Forgery

A will created through deception or outright forgery is legally void. Fraud can take several forms, such as:

• Tricking the testator into signing a will they didn’t understand
• Forging the testator’s signature
• Substituting pages or altering content after the will is signed

If fraud is suspected, handwriting experts, digital metadata, or forensic document examiners may be used to investigate. Courts take these claims very seriously — and proven fraud will almost always result in invalidation.

5. Revocation by the Testator

Sometimes a will is invalidated because the person who made it changed their mind — and legally revoked it before death.

Common methods of revocation include:

• Creating a new will that explicitly states the old one is revoked
• Physically destroying the original (e.g., tearing, shredding, burning)
• Writing a codicil that contradicts or cancels out parts of the original will

If multiple versions of a will exist, the most recent valid one usually controls — unless it’s proven to be forged, coerced, or improperly executed.

6. Missing or Destroyed Wills

If the original signed copy of the will cannot be found after death, courts may assume it was revoked — even if a digital or photocopy exists.

Unless someone can prove that the original was lost or accidentally destroyed, a copy may not be accepted in probate court.

This is why secure storage is critical. A misplaced will could be as damaging as an invalid one.

7. Disqualified Beneficiaries or Executors

In some states, certain individuals are legally prohibited from benefiting under specific circumstances. This doesn’t invalidate the entire will but may disqualify certain provisions.

Examples include:

• A caregiver who assisted in writing the will
• A witness who is also a beneficiary
• An executor who is a convicted felon (in some states)

If disqualified, their share may pass to other heirs or be governed by a fallback clause in the will.

8. Violating Public Policy

A will can also be invalidated if it includes terms that are illegal or go against public policy. Common examples include:

• Conditions that require a beneficiary to divorce, marry, or convert religions
• Instructions to commit illegal acts
• Provisions that discriminate or violate civil rights

Such clauses may be struck down individually, or they could affect the validity of the entire document depending on state law.

9. Multiple Wills Causing Conflict

If multiple wills are found, and they contradict each other without a clear revocation, legal confusion follows.

In these situations, the probate court must determine:

• Which will was executed most recently
• Whether the newer version is valid
• Whether the new will revokes the previous one

Conflicting wills can lead to full or partial invalidation of one or both documents, depending on the evidence presented.

🧠 You May Wanna Check Out:

• What Is Power of Attorney and How Does It Work?
• Can You Write Your Own Will? DIY vs Lawyer-Created Wills
• Will vs. Trust: Which One Is Right for You?

Final Thoughts

A valid will protects your wishes and gives your loved ones clarity during a difficult time. But even one small legal misstep can lead to court challenges, family disputes, or having the entire will thrown out.

Understanding what can invalidate a will helps you avoid common pitfalls — whether you’re writing your own or reviewing someone else’s. Follow the rules carefully, get legal guidance when needed, and keep your estate plan updated as life changes.