Much of the Mental Capacity Act 2005 involved a restatement of common law principles. However, in the test for capacity the law makers sought to bring together medical thinking and provide some new clarity. The test for capacity as set out in Section 3 of the Mental Capacity Act 2005 (MCA) is essentially a two-tier test. The first stage is to find a diagnosis or a medical condition that might amount to an incapacity in decision making. The test then goes on to consider whether the condition itself is such that it interferes with the function of the mind.

This approach is widely applied in many contexts, including decision making around finances, welfare issues and personal matters. However, some experts, including the previous Senior Judge of the Court of Protection – Judge Lush – felt that a more functional test, not relying on medical diagnoses should apply, as it does throughout much of Europe.

The problem with a diagnosis based approach is best illustrated through looking at the application of the test. The MCA at Section 2, following long established caselaw, confirmed that the test for capacity is decision specific. This means capacity should be reviewed in the context of each particular decision; as some decisions require a higher level of mental ability than others and capacity often fluctuates over time. For example, the level of understanding needed to marry or have sexual relations is generally thought to be at a lower level than that of being able to litigate.

Will making provides an informative example of the decision-making process. It is also in this area that judges have considered both the medical and the functional tests. The old common-law test set out in Banks v Goodfellow [1870]LR5 QB 565 was primarily a functional test. The person must understand the nature of making a will, the extent of their property and understand the moral claims which the testator should consider. If there is evidence that the testator’s ability to do this was impaired, then the Banks v Goodfellow test specifies that the assessor should consider if no disorder of the mind, poisons, or perverts their sense of right or impedes their thinking.

Which test applied was for some time uncertain. However, the courts in the case of Walker [2014] EWHC 71 (Ch) and subsequently in James v James [2o18] EWHC 43 (Ch) confirmed that the Banks v Goodfellow rules should apply to this area of decision making. Whilst not dismissing the MCA test they felt that the Banks v Goodfellow principles should be applied. However, despite the ruling some tension remains as to the correct legal principles to apply.

The recent case of Clitheroe v Bond [2020] EWHC 1185 (Ch) is interesting in that it highlights the difference between the two approaches and developments in psychiatry.

In this case Deputy Master Linwood took a Mental Capacity Act approach to determining capacity. He first looked to see whether there was a diagnosis that might impair the testator’s reasoning to the extent that it might render her incapable.

This approach would provide no problems in most cases, however here there was no lifetime diagnosis. At the hearing, two medical experts who took two different views on diagnosis. Dr S Series reviewed the medical records and noted that whilst the testator had numerous problems, there had been no diagnosis of any psychiatric condition. Indeed, there had been a formal assessment, that concluded that she was not suffering from a mental illness. Professor Jacoby’s opinion was that the testator had an affective grief disorder.

Looking at the two tests, the Mental Capacity Act refers to a medical diagnosis whereas the Banks v Goodfellow text refers to a disorder of the mind. In the Victorian era different terminology applied and so they could not have been referring to personality disorders. For example, the Court of Protection was the jurisdiction of the Masters of Lunacy. However, as psychiatry was just evolving – perhaps it still is – they were more prone to refer to describe disorders rather than mental illnesses. Coincidently, within modern psychiatry there is a growing tendency to do the same. Many find it more useful to refer to Disorders that are descriptions of a behaviour that the patient cannot control, rather than a clinical diagnosis. The reader will doubtless have heard of Eating Disorders, Personality Disorders, etc. The return to Victorian terminology is not a return to Bedlam, but perhaps a deeper understanding of the complexity of mental health.

In this case the Deputy District Judge looked for a diagnosis, but could not find one. He felt unable to choose between two equally plausible expert opinions. As such the judge looked at the burden of proof. It is well established that there is a presumption of capacity as set out in Section 1 (2) of the Act. It has also been long established, for example in the case of Steele v Calley [1831] 1Q260, that that presumption can be rebutted, where the decision calls out for an explanation. In cases where the presumption has been displaced, then it is up to the propounder of the will to prove validity as set out in Waring v Waring in 1848.

The Judge applied the burden of proof and found that as there was no clear diagnosis, the grief disorder diagnosis must apply. This is a fairly remarkable decision, bearing in mind that a grief disorder is a relatively novel diagnosis. Although there have been cases of bereavement disorder being asserted in incapacity cases, such as in the case of Key v Key in 2010, in this case the cause of the grief was some 4 years before the last will. The Deputy Master then sent on to look at the testator’s functioning and character and to consider if she was functioning in a rational manner. She was not – so the Deputy Master then went on to find a lack of capacity.

The result appears to lack internal logic – because there was no proof of a diagnosis that was proof enough of a diagnosis. The process would have been more coherent if the Banks v Goodfellow approach had been adopted. That would be a finding of fact that the testator’s reasoning and beliefs were not rational. As such, the functioning of her mind was not that of a person capable of making a will.