In April 2005, the Mental Capacity Act 2005 (MCA), which relates to England and Wales, received Royal Assent, coming into force during 2007. The MCA incorporates into statute law principles and practice that had been established, over many years, through case law. It sets out how mental capacity is defined in law and how ‘best interests’ should be ascertained when a person lacks the requisite capacity to make the decision in question.

Prior to its introduction, clinicians and carers were in uncertain legal territory when making decisions of a social, medical or financial nature for individuals without capacity. Importantly, however, the Act is more than a solution to a recognised gap in English and Welsh law; it is also about a culture change. It requires those in a caring and/or professional capacity to engage with a person who may lack decision-making capacity, in a manner that involves the person and others important to them in the process of decision-making and has regard to their past and present beliefs and values. The MCA, in its approach, is not so much giving power to others to make decisions, rather it is asking those who have to take a decision on behalf of another to do so in a manner that is transparent, justifiable and respectful of all issues relevant to that person. It is applicable in any situation where someone might lack capacity, from a person transiently incapacitated through excess alcohol or from a head injury requiring treatment, to people with potentially more enduring incapacity due to dementia or intellectual disabilities. It is therefore as relevant in intensive care as it is in social care. The MCA is about the ‘here and now’, when an immediate decision may have to be made on behalf of a person lacking capacity at the time, but also about planning for the future – how individuals, while they have capacity, can determine who can take decisions on their behalf in the event that they later lose capacity through illness or injury.

Although it was a very significant Act of Parliament, much of what the MCA has brought into practice is what practitioners and others should already have been adhering to on the basis of the developing case law.