MENTAL INCAPACITY IN WILLS: a reflection on the tests established under both common law, and the Mental Health Act 2005


In order for a will to be valid, the maker of the will (testator/testatrix) must have mental capacity.

At times as lawyers, we find ourselves on a rather sticky wicket in that it has now become increasingly common for wills to be contested based on grounds of mental incapacity.

It is evident that mental health problems, and those related to age illnesses are on the increase and for each person suffering such an illness, there comes with it the potential likelihood of more and more wills being contested.

It is vital therefore to follow what is known as the ‘golden rule’. This essentially relates to obtaining medical evidence to confirm that the testator has mental capacity at the time at which the will is drawn up.

Problems arise where the golden rule is not followed, and this often results in making an arguable case for the will in question to be contested.  Where such a problem arises, the parties or legal practitioners are required to obtain medical evidence in relation to whether or not the maker of the will did in fact have mental capacity at the time at which the will was made.  In many cases this will often not arise until several years following on from when the will was actually drawn up.


The case of Walker and another v Badmin and others [2014] All ER (D) 258 has provided supplementary judicial guidance on the approach that should ideally be taken when looking to testamentary capacity following the test outlined below by the Mental Capacity Act 2005 (MCA). This is following on from the case of Scammel v Farmer (2008) EWHC 1100 (Ch) in which Stephen Smith QC reiterated Banks v Goodfellow test which is as follows:

The testator must:

  • understand the nature of the will and its effect;
  • have some idea of the extent of the property which they are disposing under the will; and
  • be aware of the persons for whom the testator would usually be expected to provide for and be free from any delusion of the mind that would cause him reason not to benefit those people.

The MCA on the other hand, put forward a new test to ascertain whether or not the testator of the will has capacity.  It states that an individual should be assumed to have capacity unless proved otherwise.

In order to satisfy the test, it is paramount that the individual understands all of the information relevant to the decision that is being made and this includes any consequences resulting from the decision that are reasonably foreseeable.

It is worthy to note that under the MCA, a decision which may seem imprudent would not necessarily amount to a case establishing a lack of testamentary capacity.

In recent times legal professionals have been in favour of the view that the test set out in the MCA is complementary to that set out in the Banks test and does not in any event replace it.  Although there has been much debate on this issue the specific legal position as is ever the case in law, remains a grey area.

In the case of Walker v Badmin, Strauss LJ considered the tests for capacity put forward in both the Banks case and under the MCA.  He made a finding that the test set out in the MCA is more difficult to satisfy than that of the one in the case of Banks for the following reasons:

  1. The burden of proof under the MCA is that capacity is assumed unless proved otherwise;
  2. The MCA makes it a requirement that the person understands all the information relevant to the making of a decision; and
  3. For any consequences resulting from the decision to be reasonably foreseeable.

In respect of the above, it would appear that although the test set out under the MCA does raise some pertinent issues to explore when looking at mental capacity at the time of making a will, the requirements seem rather onerous and further, as stated by Strauss LJ the test outlined under the MCA could potentially invalidate wills which would not otherwise be invalidated under the common law test. This raises concerns in respect of the wishes of the deceased if a finding is made to negate the fact that the testator lacked capacity.


Therefore when considering contested wills, it will be for the Court to decide whether to prioritise the common law test set out in the case of Banks with the supplemented guidance set out in the Mental Health Act 2005.

Of course in the event that the Court finds that the testator lacked mental capacity, the will being contested is likely to be invalid and therefore any former will would instead be activated.  Where there is not a previous will, the rules on intestacy will apply.

So what does this mean for those of us who are practitioners?

In most cases, it hopefully serves as a reminder to follow the ‘golden rule’ and to act in the best interests of the client pursuant to the Solicitors Regulation Authority code of conduct in the lead up to preparation of the will.

In addition, it is always important to look at the bigger picture when taking instructions from the client in respect of the preparation of the will. It is important to consider what difficulties may later arise, in the event that the mental capacity of the testator is in doubt or not confirmed at the outset by way of medical evidence.

Simi Dhanjal
Trainee Solicito

07 April 2024

by Bhogal Partners

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