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“Capacity”: What Is It & How Do You Contest A Will Based On Incapacity?

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Perhaps this question will be asked more in the future given the unfortunate circumstances in which some Wills are being made under Covid-19 (although this topic extends far beyond).

One of the grounds for contesting a Will is incapacity. Incapacity on the part of the person making the Will can take various forms, such as dementia.

Someone who does not have the mental capacity to make a legally valid Will may also come under the undue influence during the process of making it.

This undue influence can also become grounds for contesting a Will.

Can Someone With Dementia Legally Write a Will?

A dementia diagnosis does not, in itself, prevent someone from making important decisions, including making their Will.

However, as dementia symptoms worsen over time, they might then lack mental capacity to make decisions about things such as finances, health or welfare.

What is crucial when making a Will if a person has dementia is whether they are able to understand the Will and make decisions about it.

This is known as having testamentary capacity.

To have testamentary capacity, an individual must be able to understand:

  • what making a will means and the effect it will have
  • what they own and how this might change, such as whether they owe money or someone owes money to them
  • who they would name as beneficiaries in their Will, and why they would choose to leave something to them.

A Will made by someone with dementia could be found to be invalid if it could be shown that at the time they made the Will they did not have testamentary capacity.

You could then contest a Will based on the mental incapacity of the Will maker.

The best way to ensure that a person who is making a Will has testamentary capacity is to seek a report from their doctor or an independent expert…

at the time when they are giving instructions to confirm that they have the relevant testamentary capacity to do so.

This can be particularly important if someone has a known condition that could affect their capacity, if they are particularly elderly or if they are recently bereaved or have been unwell physically.

How Can You Prove Incapacity?

Legally, a Court is only interested in the mental incapacity of the person who has made the Will (the testator) at the time they made it.

Therefore, medical records are likely to play a large part in providing evidence. A medical expert will be needed to prepare a report based on this evidence and statements made about the condition of the testator when they were making the Will.

Because dementia is a degenerative disease, its effects can vary from day to day – pinpointing the condition of the person making the Will when they made it is critical.

How Do You Contest a Will Due to Undue Influence?

Again, in relation to the incapacity of the person making the Will, it is important to gather evidence about how this might have made them susceptible to undue influence.

For undue influence to have occurred, there must have been a degree of coercion.

Possible indicators that there has been undue influence might include:

  • The Will might contain unexpected or last minute changes
  • It might include wishes different to those the testator has expressed previously
  • A beneficiary not previously named, or who was due to get a smaller share of the estate now appears to be the main beneficiary.

There can be suspicious circumstances that nevertheless do not amount to undue influence. Questionable conduct arising from appeals on the part of beneficiaries to the Will maker do not necessarily mean anyone has exercised undue influence.

Essentially, the burden of proof comes down to demonstrating that the person was making the Will against their own wishes because they felt it was something they must do.

Proving that a Will has been made as a result of undue influence is very difficult as the evidence to prove why the Will was made in the way it was is often not available. Cases have succeeded on this ground but they are rare.

This is why it is important to get professional, legal advice and support.

You should talk to your own solicitor if you need advice, but it’s wise to make sure they are a specialist Contentious Probate lawyer, or feel free to call us on 0800 088 6004 where our specialist team would be pleased to help.

Alternatively, fill in our online contact form: We’ll be in touch as soon as possible.

Nadia Halliday


Nadia Halliday

Senior Associate & Head of Contentious Probate

Nadia is a Senior Associate and heads up the contested probate department. Nadia qualified in 2008 and is an experienced civil, commercial and  contested  probate solicitor having built up something of a niche practice area for this type of work. With an ability to advise…