Ethics & law
Assessing mental capacity in practice
How to navigate the laws around capacity
Patients require capacity, sufficient information, and freedom from coercion to give consent to medical investigation or treatment. Capacity is defined as the mental ability to make and communicate a decision, and it is estimated that 26-40% of medical inpatients lack capacity because of mental illness, learning disability, or a medical condition that affects brain function, such as delirium or head injury.123
Most countries have a legal framework for assessing capacity and guiding decisions relating to incapacitated people. In the UK, there is separate legislation in England and Wales, Scotland, and Northern Ireland. We will cover the Mental Capacity Act (MCA) 2005,4 which was enacted in England and Wales in 2007 (box 1). The law in Scotland5 and Northern Ireland6 is outlined in box 2. All doctors have a legal responsibility to understand and work within the legislation in their country or state.
Decisions about the medical and social care of