Introduction

The Mental Capacity Act 2005 (‘the Act’) provides a comprehensive legal framework for determining whether a person (‘P’) lacks capacity to make a particular decision and, if so, what decision(s) should be made on their behalf. Any decision must be made in P's best interests. The Act is supported by the Mental Capacity Act Code of Practice (2007) (‘the Code’), which provides guidance about how the Act should be applied. The Act was the culmination of long process of consultation beginning in 1989 when the Law Commission for England and Wales undertook a review of the law. In June 2004, the Mental Capacity Bill was introduced to Parliament and it contained a new clause prescribing five principles, which were incorporated into the Act at s 1. The Act aims to maximise P's participation in the decision-making process.

P will lack capacity if they are ‘unable to make a decision for [them]self in relation to the matter because of an impairment of, or a disturbance in the functioning of, the mind or brain’ (s 2; known as the ‘diagnostic threshold’). The starting point is that a person has capacity to make the particular decision in question (s 1(2)). P is unable to make a decision for themself if they cannot undertake any one of the four aspects of decisionmaking prescribed by s 3(1). There is no concept of ‘general incapacity’ and capacity must be assessed in relation to the specific decision at the time the decision needs to be made.

The Law Commission identified that ‘[n] o statutory guidance could offer an exhaustive account of what is in a person's best interests … the individual person and his or her individual circumstances should always determine the result’. Decision-making in P's best interests must consider ‘all the relevant circumstances’ (s 4(2)) and must ‘in particular take the following steps’ (s 4(2)):

• • consider whether a best interests decision should be delayed if it is likely that P will have capacity in relation to the matter in question (s 4(3));

• • permit and encourage P to participate, or to improve her ability to participate, as much as possible (s 4(4));

• • not be motivated by a desire to bring about P's death (s 4(5));