How an 'insane delusion' can threaten the validity of a will in England and Wales

Under English law, individuals have an unusually high degree of testamentary freedom. A person making a will (a 'testator') can be anything from capricious to cruel. They can make decisions which family members justifiably feel are unfair.

 But when does the basis for that decision to be unfair signify a mental health issue that could result in the will being declared invalid?

What is an 'insane delusion'?

The test for whether a person is capable of making a valid will comes from the 1870 case of Banks v Goodfellow.  One of the test's requirements is that decisions must not have been affected by 'insane delusions' or a 'disorder of the mind'.  Over 150 years on, the language around mental health has moved on, but the test remains. 

Importantly, it is not sufficient to invalidate a will for the testator to have been mistaken, exaggerating the truth, or even rewriting history to justify a controversial decision.  A delusion must be both false and fixed – belief in it must endure. 

Although there can be overlap with cases involving elderly testators, where mental health issues such as dementia may play a part in undermining the decision to make a particular will, a striking feature of some of the cases is that relatively young and superficially capable testators can be subject to 'insane delusions' that undermine a will. 

The existence of a mental disorder first needs to be established.  Sometimes this will be evident from the medical history or records; in other cases, the only evidence of the disorder might be the delusions themselves. 

Also key is a connection between the delusion and the will.  In the case of Banks v Goodfellow itself, the testator was certainly suffering from a disorder of the mind – he believed that he was being visited by devils and harassed by a dead neighbour – but because these 'insane delusions' had not actually affected the content of his will, the will was valid.  By contrast, in the 2007 case of Kostic v Chaplin, Mr Kostic left his entire estate to the Conservative Party. He believed that his family were embroiled in a global conspiracy from which only Margaret Thatcher could save him: 'Our Prime Minister is the greatest Leader of the Free World in the human [peacetime] history … God knows when we shall have again such a unique and genius person'. This clearly influenced his decision to disinherit his family to prevent his substantial wealth ending up 'in the hands of destructive people – Satanic Monsters', so his will was not valid.

Not all delusions are so dramatic.  In the case of Ritchie v Joslin, the testatrix Mary disinherited her children because she believed - to quote the solicitor who drafted the will -  'none of them have shown her any kindness over the last few years… her daughter Margaret never comes near her now'.   But this was not true: both daughters visited their mother regularly and she depended upon the care they gave her.  Accordingly, the will was invalid.  

The line between irrationality and delusion can be hard to draw.  A person suffering from a delusion may express it in a perfectly coherent and reasonable way.  If the listener does not know the truth they may have no idea that something is wrong - often the case when an independent solicitor prepares a will knowing only what their client tells them.   

How will the court approach delusions?

A will made by a person suffering from delusions often appears rational: it makes sense to an objective reader, even if a person with first-hand knowledge could see that something was amiss.  

In those circumstances, the court will proceed on the basis that the will was validly made by a testator with capacity, and it will be for the person challenging the will to raise a real doubt to the contrary.

To do so, a claimant will need to establish both: (1) that the reasoning behind the will did not reflect reality; and (2) that this was caused by illness as opposed to (for example) a mistake which the testator would have accepted if it had been pointed out to them.

What to do if a delusion is suspected?

If you feel strongly that something is wrong with a will, you first need to understand the reasons behind the testator's decisions.  The drafting solicitor's file is important in this. A testator is under no obligation to explain themselves but a good solicitor will have discussed their intentions with them and recorded any reasons they did give.  The solicitor should have taken particular care to do so in circumstances where the testator was excluding close family members or those who might otherwise have expected to benefit.  

Once you know the reasons behind the will, you will be in a better position to consider whether there may have been a 'delusion' at work.  

Can you identify a false belief and demonstrate why it is false?  For example, if a testator believed that their children had severed contact, family members may be able to produce objective evidence to the contrary such as phone logs, text messages and birthday cards.  It will be helpful if there is evidence that the testator had been challenged about the false belief and stuck to it, but this is not an essential evidential requirement: as confirmed in the 2022 appeal decision in Clitheroe v Bond, it is possible for the court to draw an inference that the testator will have been aware of clear evidence to the contrary and yet they maintained a false belief despite this.

Often, the more difficult aspect is linking the false beliefs to a medical condition.   If the testator was diagnosed with a mental health condition during their lifetime, you may be able to draw a link to that condition.  It may be necessary for a medical expert to give an opinion on the link. If there is no record of any diagnosis, a medical expert can review medical records and factual evidence and express an opinion on the testator's mental health when they gave their instructions.  

When you know that a will has been made on a false basis, it can seem a matter of common sense that the testator was acting irrationally and the will should not stand.  The reality is more complicated.

Under English law, testators are entitled to be irrational, unfair, and plain wrong. This will not be taken as evidence that they lack capacity unless their decision-making can only be explained by mental disorder.

Potential claimants who think that a 'delusion' may have impacted a testamentary decision need to consider carefully how the fact pattern interacts with the deceased's health.  This can involve detailed analysis of the solicitor's file and other documentary evidence, as well as witness and medical evidence.