How Can Dementia Diagnosis Invalidate Wills in 2026?

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A dementia diagnosis does not automatically invalidate a Will in 2026; the legal focus is on “Testamentary Capacity” at the specific moment the Will was executed. Under the Banks v Goodfellow test, a testator must understand the nature of the Will, the extent of their estate, and the moral claims of potential beneficiaries. If a solicitor follows the “Golden Rule” by obtaining a medical professional’s opinion during drafting, the Will is significantly harder to challenge.

dementia diagnosis

The Distinction Between Medical Diagnosis and Legal Capacity

In 2026, the UK courts maintain a sharp distinction between a clinical diagnosis of cognitive impairment and the legal threshold for “Testamentary Capacity.” A person may suffer from early-stage Alzheimer’s or vascular dementia and still possess the “lucid interval” necessary to execute a valid Will. The court does not ask if the testator was “ill,” but rather if their mind was “sound” enough to understand the specific legal act of disposing of their property. As long as the testator understands the consequences of the document they are signing, the Will remains valid regardless of a medical label.

The Banks v Goodfellow Test: Still the Gold Standard

Despite the passage of over 150 years, the 1870 case of Banks v Goodfellow remains the definitive test for capacity in 2026. This common law test requires the testator to meet four criteria: they must understand the nature of the act (making a Will), understand the extent of the property they are disposing of, comprehend the moral claims they ought to give effect to, and be free from any “disorder of the mind” that poisons their affections. Failure to meet even one of these criteria can lead to the entire Will being declared void by the High Court.

The 2026 Conflict: Common Law vs. The Mental Capacity Act 2005

A significant point of technical contention in 2026 is the interplay between the Banks v Goodfellow test and the Mental Capacity Act 2005 (MCA). While the MCA is used for “living” decisions (like Lasting Powers of Attorney), the courts have confirmed that the older common law test still governs the validity of a Will after death. However, modern judges frequently use the MCA as a “cross-check” or supportive framework. An “Elite” legal challenge often leverages the nuances of both tests to highlight inconsistencies in how the testator’s capacity was assessed at the time of signing.

The “Golden Rule” for Solicitors and Medical Reports

To prevent expensive litigation, 2026 probate practitioners strictly adhere to the “Golden Rule” established in Kenward v Adams. This rule suggests that when a testator is aged or has suffered a serious illness, the solicitor should seek a contemporaneous medical report from a GP or psychiatrist to confirm capacity. If Mr. Bal, as your solicitor, follows this rule, it creates a “presumption of validity” that is extremely difficult for disgruntled beneficiaries to overturn. Conversely, the absence of a medical report for a frail testator is often the first “red flag” we look for when initiating a contest.

The Power of “Lucid Intervals” in Probate Law

Many dementia patients experience “fluctuating capacity,” where they are confused in the evenings (often called “sundowning”) but remarkably clear in the mornings. In 2026, the law recognizes these “lucid intervals.” If it can be proven, via caregiver logs, medical notes, or witness testimony, that the Will was signed during a period of clarity, the Will is legally binding. This is why the testimony of the attesting witnesses is crucial; they provide the “on-the-ground” evidence of the testator’s state of mind at the exact moment the pen touched the paper.

Delusions and the “Poisoning of Affections”

Capacity isn’t just about memory; it’s about the absence of “insane delusions.” In 2026, we see cases where a testator is physically healthy but suffers from a fixed, false belief, for example, believing a child has been stealing from them when no such thing occurred. If this delusion “poisons” the testator’s mind and causes them to disinherit that child, the Will can be set aside for lack of capacity. This is technically distinct from “undue influence,” as the pressure comes from within the testator’s own disordered mind rather than an external person.

Burden of Proof: Who Must Prove Capacity?

The burden of proof in 2026 follows a specific “ping-pong” sequence. Initially, if a Will appears rational and was properly executed, capacity is presumed. However, if the person contesting the Will raises a “real doubt” (e.g., by producing a medical record of a stroke or a dementia diagnosis), the burden of proof shifts back to the executors of the Will. They must then prove, on the balance of probabilities, that the testator did indeed have the requisite capacity. This shift is a massive tactical advantage for those challenging a Will.

The “Parker v Felgate” Exception: Signing While Failing

A rare but vital rule in 2026 is the principle from Parker v Felgate. This allows a Will to be valid even if the testator lost capacity between giving instructions and signing the final document. If the testator had capacity when they gave the instructions to the solicitor, and at the time of signing they understood they were executing the Will they previously ordered, the court may uphold it. This rule protects those whose health declines rapidly during the drafting process, provided the solicitor acted with due diligence.

Digital Evidence: Smart Devices as 2026 Witnesses

In 2026, we increasingly use digital “behavioral markers” to prove or disprove capacity. We analyze a testator’s smart home interactions (like Alexa logs), their ability to navigate online banking, or the complexity of their text messages. If a testator was successfully managing an online investment portfolio or consistently using Uber at the time the Will was signed, this serves as strong “real-world” evidence of high-level cognitive function that can override a generic dementia diagnosis in the eyes of a judge.

The Costs of Challenging for Capacity

Challenging a Will for lack of capacity is an expensive undertaking in the UK. Unlike other forms of litigation, if there were “reasonable grounds” for the doubt, such as a confusing medical history, the court may order that the legal costs for both sides be paid out of the estate itself. However, if the challenge is deemed frivolous or purely “fishing for evidence,” the person bringing the claim could be hit with a massive personal costs order. Professional mediation is almost always recommended in 2026 before the case reaches the High Court.

The Role of the Larke v Nugus Statement

When capacity is questioned, the first step is always to request a Larke v Nugus statement from the solicitor who drafted the Will. This is a detailed account of the circumstances surrounding the Will’s execution. It reveals whether the solicitor saw the testator alone, how they checked for capacity, and what notes they took regarding the testator’s understanding of their assets. In 2026, a “thin” or poorly documented solicitor’s file is the most common reason Wills are successfully overturned for lack of capacity.

FAQs

Q1: My father had a stroke two days before signing his Will. Is it still valid?

A stroke does not automatically revoke capacity, but it raises a significant “doubt.” The court will look at whether the stroke affected his speech (aphasia) or his actual cognitive understanding. If he was able to communicate his wishes clearly, even through non-verbal means, and understood the “Banks v Goodfellow” criteria, the Will can be upheld.

Q2: Can a GP’s letter prove my mother had capacity?

A GP’s letter is strong evidence, but it is not infallible. In 2026, judges often prefer the testimony of a specialist geriatric psychiatrist over a general practitioner. If the GP’s assessment was brief (e.g., a “mini-mental state exam”), a legal specialist may still be able to challenge it by showing the GP didn’t specifically test for testamentary capacity.

Q3: What if the witnesses to the Will say the testator seemed “confused”?

Witness testimony is a “primary” source of evidence. If the two people who stood in the room during the signing testify that the testator didn’t know where they were or didn’t recognize the document, it is extremely difficult for the executors to prove capacity. This is why choosing independent, professional witnesses is so important in 2026.

Let’s Do This Together

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To our team, this process is not about winning; it’s about claiming what was yours from the beginning.

Get your free, no-obligation case assessment. Call 08002980029 or visit contestawilltoday.com

Check our complete guide on how to contest a will in 2026, and arm yourself with the needed knowledge here!

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Frequently asked questions.

Disputes over wills can arise in several circumstances, including:

  • Testamentary capacity: The person who made the will (known as the testator) must have had the mental capacity to understand what they were doing and the consequences of their actions. This means that they must have been able to understand the nature and extent of their property, the people they were giving their property to, and the people they were excluded from their will.

 

  • Valid execution: The will must have been executed correctly under the law. This means it must be in writing, signed by the testator, and witnessed by two independent witnesses.

 

  • Undue influence: The testator must have made the will freely and without any pressure from others. The will may be invalid if someone was unduly influenced to make a will. Undue influence can occur when someone takes advantage of a testator’s vulnerability, such as if the testator is elderly, ill, or has a mental disability.

 

  • Fraud or forgery: If the will was forged or if someone fraudulently induced the testator to make the will, the will may be invalid.

 

Claims against a will must usually be made within six months of the grant of probate being issued. This is the legal document that gives the executor the authority to administer the estate. If a claim is not made within this time, it may be too late to challenge the will.

As such, executors often wait until this six-month period has expired before distributing the estate. This is to avoid having to distribute the estate and then having to take it back if a successful claim is made against the will.

Here are some examples of how these disputes can arise:

  • A family member may dispute a will if they believe that the testator did not have the mental capacity to make a will. For example, if the testator was suffering from dementia or Alzheimer’s disease at the time the will was made.
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A family member may dispute a will if they believe that it was not executed correctly. For example, if the will is not signed by the testator or if it is not witnessed by two independent witnesses.

 

  • A family member may dispute a will if they believe that they were unduly influenced to make the will. For example, if a caregiver or another family member pressured the testator to make the will in their favour.

 

  • A family member may dispute a will if they believe that it was forged or if someone fraudulently induced the testator to make the will. For example, if someone forged the testator’s signature on the will or if someone lied to the testator about the contents of the will.

If you are thinking about disputing a will, it is important to seek legal advice as soon as possible. We can assess your case and advise you on your legal options.



Types of Trusts

Many different types of trusts can be set up, depending on your specific needs and goals. Some of the most common types of trusts include:
Bare Trusts: A bare trust is a simple type of trust in which the trustee holds the assets for the benefit of the beneficiary. The beneficiary is entitled to the income and capital of the trust as soon as they are old enough to receive them.

Interest in Possession Trusts: An interest in possession trust is a type of trust in which the beneficiary is entitled to the income from the trust immediately, but not to the capital until a later date. This type of trust is often used for minor beneficiaries or for beneficiaries who are not yet responsible enough to manage their own money.

Discretionary Trusts: A discretionary trust is a type of trust in which the trustee has the discretion to decide how and when to distribute the income and capital of the trust to the beneficiaries. This type of trust is often used for families with multiple beneficiaries or beneficiaries with special needs.

Accumulation Trusts: An accumulation trust is a type of trust in which the income from the trust is accumulated and not distributed to the beneficiaries until a later date. This type of trust is often used to save for a specific purpose, such as a child’s education or a retirement fund.

Mixed Trusts: A mixed trust is a type of trust that combines elements of different types of trusts. For example, a trust may be a discretionary trust for one beneficiary and an interest in possession trust for another beneficiary.

Settlor-Interested Trusts: A settlor-interested trust is a type of trust in which the settlor (the person who creates the trust) retains some interest in the trust assets. For example, the settlor may retain the right to receive income from the trust or to appoint the trustee.

Non-Resident Trusts: A non-resident trust is a type of trust that is created and governed by the laws of a country other than the country where the settlor or beneficiaries reside.
Which type of trust is right for you will depend on your specific needs and goals. It is important to consult with an estate planning attorney to discuss your options and choose the type of trust that is best for you.
Here are some examples of how different types of trusts can be used:
A bare trust can be used to hold assets for a minor child until they reach the age of majority.

An interest in possession trust can be used to provide income to a beneficiary who is not yet responsible enough to manage their own money.

A discretionary trust can be used to manage assets for a family with multiple beneficiaries or for beneficiaries with special needs.

An accumulation trust can be used to save for a specific purpose, such as a child’s education or a retirement fund.

A mixed trust can be used to achieve a variety of different goals, such as providing income to one beneficiary and preserving capital for another beneficiary.

A settlor-interested trust can be used to retain some control over trust assets after the settlor has created the trust.

A non-resident trust can be used to reduce estate taxes or to protect assets from creditors.
It is important to note that this is just a brief overview of the different types of trusts. There are many other types of trusts available, and each type of trust has its own specific features and benefits. For more information please visit www.gov.uk/trusts-taxes/types-of-trust

Inheritance trust disputes can be complex and varied, but some common scenarios include:

  • Disputes over the validity of the trust: This can happen if the settlor (the person who created the trust) does not have the mental capacity to create a trust, or if the trust deed was not executed correctly.

 

  • Disputes over the interpretation of the trust deed: If the trust deed is poorly drafted or unclear, it can lead to disputes between the trustees and beneficiaries about how the trust should be administered.

 

  • Disputes over the appointment or removal of trustees: Trustees have a legal duty to act in the best interests of the beneficiaries. If a trustee is not acting in the best interests of the beneficiaries, the beneficiaries may apply to the court to have the trustee removed.

 

  • Disputes over the investment of trust assets: Trustees have a legal duty to invest trust assets prudently. If a trustee makes investments that are too risky or that lose money, the beneficiaries may sue the trustee for breach of duty.

 

  • Disputes over the distribution of trust assets: Trustees have a legal duty to distribute trust assets to the beneficiaries in accordance with the terms of the trust deed. If a trustee distributes trust assets incorrectly, the beneficiaries may sue the trustee for breach of duty.

 

Here are some specific examples of inheritance trust disputes that have occurred in the UK:

  • In one case, a beneficiary disputed the validity of a trust deed on the grounds that the settlor (the person who created the trust) did not have the mental capacity to create a trust at the time it was set up.

 

  • In another case, a beneficiary sued the trustees for breach of duty after the trustees made a number of risky investments that lost money.



  • In a third case, a beneficiary sued the trustees for breach of duty after the trustees distributed trust assets to the beneficiaries in a way that was not in accordance with the terms of the trust deed.

 

Other possible disputes include:

  • A beneficiary was expecting more than what is set out in the trust document. This may be because the beneficiary had a reasonable belief that they would receive more, or because the trust document is unclear about the beneficiary’s entitlement.

 

  • The individual who set up the trust was provided with negligent or misleading advice. If the settlor was not properly advised about the consequences of setting up a trust, or if they were given incorrect information, they may be able to challenge the trust.

 

  • The trust document is either incomplete or unclear about the wishes of the deceased. If the trust document is incomplete or unclear, it can lead to disputes between the trustees and beneficiaries about how the trust should be administered.

 

  • A trustee acts against the best interests of the beneficiary or doesn’t administer the trust correctly. Trustees have a legal duty to act in the best interests of the beneficiaries. If a trustee breaches their duty, the beneficiaries may sue the trustee.

If you are involved in an inheritance trust dispute, it is important to seek legal advice as soon as possible. We can assess your case and advise you on your legal options.

Contesting a will is challenging the validity of a will. This can be done on a number of grounds, including.

  • The testator (the person who made the will) did not have the mental capacity to make a will.
  • The will was not executed correctly, i.e., it was not signed by the testator or witnessed by two independent witnesses.
  • The testator was unduly influenced to make the will.
  • The will was forged or fraudulent.

 

Contentious probate is any dispute about the administration of a deceased person’s estate. This can include disputes about

  • The validity of the will.
  • The interpretation of the will.
  • The appointment or removal of executors.
  • The distribution of the estate assets.
  • The management of the estate.
  • In the UK, contentious probate is dealt with by the High Court.

 

The main difference between contesting a will and contentious probate is that contesting a will is specifically challenging the validity of the will, while contentious probate can include a wide range of disputes about the administration of an estate.

Here is an example:

Contesting a will: A beneficiary challenges the validity of a will on the grounds that the testator did not have the mental capacity to make a will.

Contentious probate: A beneficiary disputes the interpretation of a will and argues that they are entitled to a larger share of the estate than they have been given.

It is important to note that the two terms are often used interchangeably. For example, a lawyer might say that they are “dealing with a contentious probate matter” when they are actually challenging the validity of a will.

If you are thinking about contesting a will or pursuing a contentious probate claim, it is important to seek legal advice as soon as possible. We can assess your case and advise you on your legal options.

The time limit for making a contentious probate claim in the UK is six months from the grant of probate. This is the legal document that gives the executor the authority to administer the estate.

If you do not make your claim within this six-month time limit, you may need to apply to the court for permission to make a late claim. The court will only grant permission if you have a good reason for not making your claim on time.

There are a number of factors that the court will consider when deciding whether to grant permission for a late claim, including:

  • Why did you not make your claim on time?
  • The strength of your case.
  • Whether the other beneficiaries will be prejudiced if your claim is allowed to proceed.
  • If the court grants you permission to make a late claim, you will need to file your claim within 28 days.

 

It is important to note that there are some exceptions to the six-month time limit. For example, if the executor has committed fraud or concealed assets from the beneficiaries, the beneficiaries may be able to make a claim after the six-month time limit has expired.

If you are thinking about making a contentious probate claim, it is important to seek legal advice as soon as possible. A lawyer can assess your case and advise you on the time limits that apply and whether you have a good case.

Here are some examples of when you might be able to make a late contentious probate claim:

  • You were not aware of the death of the deceased until after the six-month time limit had expired.
  • You were unable to make your claim on time because you were ill or incapacitated.
  • The executor has deliberately concealed information from you about the estate.
  • The executor has committed fraud in the administration of the estate.

 

The 12-year limit for making a contentious probate claim in the UK applies to claims for reasonable financial provision under the Inheritance (Provision for Family and Dependents) Act 1975. This means that if you are making a claim for financial provision from an estate, you must do so within 12 years of the date of the deceased’s death.

The reason for the 12-year limit is to encourage people to make their claims as soon as possible after the deceased’s death. This is because it can become more difficult to investigate and prove a claim after a long period of time has elapsed.

If you are unsure whether you are able to make a late contentious probate claim, you should seek legal advice.

Most disputes in the UK are resolved out of court through mediation and negotiation. This is because it is generally faster, cheaper, and less stressful for all involved.

If you are considering disputing a will, it is important to contact a contentious probate specialist before you involve any other relatives or beneficiaries of the estate. A specialist lawyer can advise you on your legal options and help you to resolve the dispute quickly and efficiently.

Here are some of the benefits of resolving a will dispute out of court:

  • It is faster and cheaper than going to court.
  • It is less stressful for all involved.
  • It allows you to maintain relationships with other family members and beneficiaries.
  • You have more control over the outcome of the dispute.

 

There are a number of steps that you can take to try to resolve a contentious probate dispute without going to court, including

  • Negotiation: You can try to negotiate a settlement with the other parties to the dispute. This may involve making concessions on your part, but it can be a good way to avoid the time and expense of court proceedings.
  • Mediation: Mediation is a process where an independent mediator helps the parties to reach a mutually agreeable settlement. Mediation can be a good way to resolve a dispute without going to court, but it is important to note that it is not binding on the parties.
  • Arbitration: Arbitration is a more formal process than mediation, and it is binding on the parties. However, it can still be a good way to resolve a dispute without going to court.

 

If you are unable to resolve the dispute amicably, you will need to file a claim with the High Court. The court will then hold a hearing to decide the case.

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