Assessing capacity in cases of fluctuating decision-making ability

The Mental Capacity Act 2005 sets out a framework for assessing decision-making capacity and this is supported by the Mental Capacity Act Code of Practice (Department for Constitutional Affairs, 2007). The Court of Appeal in Re T (Adult: Refusal of Treatment) [1992] held that the right to make decisions presupposes an ability or capacity to do so. The presumption in law is that adults and young people have the capacity to consent to an examination and treatment and it is for the nurse to show otherwise through an assessment of decision-making capacity (Mental Capacity Act 2005, section 1).

Capacity is the key to autonomy and the test of capacity under the Mental Capacity Act 2005 is based on a test of understanding that requires the person to understand information relevant to the decision, to retain that information and to use the information when making a decision that they communicate to the nurse (Mental Capacity Act 2005, section 3). It is not a professional or status test and a nurse cannot assume a patient lacks capacity because of that person's age, physical appearance, condition or other aspect of their behaviour (Mental Capacity Act 2005, section 2).