Mental Capacity Act Basics

The Mental Capacity Act is built on five core principles that must guide all decisions made under it:

1. Presumption of capacity — Every adult must be assumed to have capacity to make a decision unless it is established that they lack capacity. Capacity must never be assumed to be absent because of age, disability, or diagnosis.
2. Right to be supported to make decisions — All practicable steps must be taken to help a person make their own decision before concluding they lack capacity. This might mean using simpler language, visual aids, or waiting until a better time of day.
3. Right to make unwise decisions — A person is not to be treated as lacking capacity merely because they make an unwise or eccentric decision. Adults have the right to make choices others disagree with.
4. Best interests — Any act done or decision made for someone who lacks capacity must be done in their best interests (see the Best Interests guide).
5. Least restrictive option — Before doing something or making a decision, regard must be had to whether there is a less restrictive way of achieving the desired purpose.

Under the MCA, a person lacks capacity in relation to a specific decision if at the relevant time they are unable to make the decision because of an impairment of, or a disturbance in, the functioning of the mind or brain. The capacity test has two stages:

Stage 1 (diagnostic) : Is there an impairment of, or disturbance in, the functioning of the mind or brain? This could be dementia, brain injury, mental illness, learning disability, substance intoxication, or any other cause.

Stage 2 (functional): As a result, is the person unable to: understand the information relevant to the decision; retain that information; use or weigh it as part of the decision-making process; or communicate their decision (by any means)?

Both stages must be satisfied for a finding of incapacity. Incapacity is decision-specific — a person may lack capacity for complex financial decisions but retain capacity for decisions about daily care, food preferences, or social activities.

The Deprivation of Liberty Safeguards (DoLS) are a set of checks under the MCA that protect people in care homes and hospitals who lack capacity and whose care arrangements amount to a deprivation of their liberty. Following the Supreme Court's landmark judgment in Cheshire West (2014), the threshold for deprivation of liberty is low — many arrangements that had not previously been considered restrictive were found to cross the threshold.

DoLS require care homes and hospitals to apply to the supervisory body (the local council for care homes; NHS England for hospitals) for authorisation of the deprivation of liberty. The authorisation process includes independent assessments of mental health, mental capacity, and best interests. Unauthorised deprivations of liberty are unlawful.

DoLS is being replaced by the Liberty Protection Safeguards (LPS), a reformed system under the Mental Capacity (Amendment) Act 2019. As of April 2025, LPS implementation is ongoing — check current status, as the transition affects how assessments are conducted.

The Mental Capacity Act 2005 Code of Practice is a statutory document — it does not just provide guidance, it imposes obligations on everyone who works with or cares for people who may lack capacity. Certain categories of people are legally required to "have regard to" the Code. These include paid care workers, healthcare professionals, social workers, attorneys under LPAs, deputies, and anyone who is paid to act in a professional capacity in relation to a person who may lack capacity. Voluntary carers and family members are not legally required to follow the Code, but it is strongly recommended as a source of practical guidance.

The Code covers every aspect of MCA practice in detail, including:

• How to assess capacity and what to record;
• How to make best-interests decisions, including consulting family and others;
• When to instruct an Independent Mental Capacity Advocate (IMCA);
• How the Court of Protection and Office of the Public Guardian work;
• How advance decisions to refuse treatment should be treated;
• How the Deprivation of Liberty Safeguards apply and when to use them.

If a professional fails to follow the MCA Code of Practice, this can be raised as a complaint with their employer, their professional regulator (the Nursing and Midwifery Council, the General Medical Council, the Health and Care Professions Council, or Social Work England, depending on their profession), or the relevant ombudsman. Failure to follow the Code is not itself a criminal offence but can constitute professional misconduct and can be evidence of a breach of the MCA.

The Code is available free online from the government's website. If you are caring for or advocating for someone who lacks capacity, reading the relevant chapters of the Code is strongly recommended. Age UK and the Social Care Institute for Excellence (SCIE) also publish accessible summaries of MCA rights and duties.