The Legal Test for Mental Capacity

What is Mental Capacity?

In the legal context mental capacity is the ability to make decisions. Examples of the situations in which it might be particularly important to establish a person's mental capacity include when in relation to making a will, undertaking lifetime giving or making a lasting power of attorney. Establishing mental capacity (or incapacity) might also be particularly important in relation to decisions about an individual's physical well-being, including about the medical treatment he/she is to receive. It might also be relevant in relation to more humdrum decisions about an individual's everyday activities and lifestyle. The test of mental capacity here is a legal test rather than a medical test or diagnosis. And what is important in assessing mental capacity is to focus on the processes by which a decision is made, rather than on the decision itself.

What is the Legal Test for Mental Capacity?

The Mental Capacity Act 2005 ("MCA") which came into force on I October 2007 creates a statutory test for capacity. This test applies for the purposes of the Act. Situations covered by the Act in which the statutory test is therefore relevant include the determination whether an individual has capacity to enter into an advance decision (by which such person sets out the circumstances in which they would not want to receive medical treatment in the event of loss of capacity) or to enter into a lasting power of attorney. It is also relevant to the appointment of a so-called independent mental capacity advocate and to the Court of Protection's power to make orders in the event that a person lacks capacity. Under this statutory test anyone claiming that a person lacks capacity must be able to show on a balance of probabilities (that is, there is a more than 50% likelihood) that this is the case.

The MCA 2005 provides that a person lacks capacity in relation to a matter if he/she is unable to make a decision for him/herself in relation to the matter because of an impairment of or disturbance in the functioning of the mind or brain. This is therefore a two-stage test. First it is necessary to ask "Does the person have an impairment of, or a disturbance in the functioning of their mind or brain?" Such impairment or disturbance may be permanent or temporary. It might be caused, for example, by significant learning disabilities, physical medical conditions that cause confusion, loss of consciousness, delirium, the symptoms of alcohol or...