In plain English
The Mental Capacity Act 2005 governs decision-making for adults whose capacity is or may be impaired. Its five principles protect autonomy and direct best-interests decisions where capacity is lacking. The Act applies in England and Wales; Scotland and Northern Ireland have parallel legislation.
The five principles
The Mental Capacity Act 2005 (England and Wales) sets out five guiding principles for any decision involving someone whose capacity is in question:
- Presumption of capacity: every adult is presumed to have capacity to make a decision unless proved otherwise;
- All practical steps to support decision-making: provide information in the right format, at the right time, with the right support;
- The right to make unwise decisions: a decision that seems unwise is not, in itself, evidence of incapacity;
- Best interests: where someone lacks capacity, decisions must be made in their best interests;
- Least restrictive option: any decision should be the option that least restricts the person's rights and freedom.
Assessing capacity
This page covers the legal framework. For the clinical service, including how to commission a formal assessment for a Will, an LPA, residence or treatment, see capacity assessment.
Capacity is decision-specific and time-specific. The two-stage test:
- Is there an impairment of, or disturbance in, the functioning of the mind or brain?
- If so, does this impairment mean the person cannot make the specific decision at the relevant time, judged against:
- Understanding the information relevant to the decision;
- Retaining the information long enough to use it;
- Using or weighing the information;
- Communicating the decision (by any means).
If any one of these is impaired and the impairment is due to a disturbance of mind or brain, capacity is lacking for that specific decision.
Best-interests decisions
Where the person lacks capacity, decisions are made in their best interests. The Act requires the decision-maker to consider:
- The person's past and present wishes and feelings;
- Any beliefs and values that would have influenced their decision;
- Other factors they would have considered;
- The views of carers, family, friends, and any attorneys;
- Whether the person might regain capacity;
- The least restrictive option.
Who makes the decision
The decision-maker depends on the type of decision:
- Health and welfare: the responsible clinician, in consultation with family and any health and welfare attorney;
- Property and finance: a property and finance attorney (LPA) or, if no LPA, a Court-appointed Deputy;
- Day-to-day decisions (food, clothes, simple care): the carer providing the care;
- Serious medical treatment: where there is no attorney and no family, an Independent Mental Capacity Advocate (IMCA) is appointed.
What the Act does not do
The Mental Capacity Act does not allow:
- Forced treatment as a routine response to refusal (the Act protects autonomy, not paternalism);
- Deprivation of liberty without specific legal authority (Deprivation of Liberty Safeguards apply);
- Decisions that contradict a valid Advance Decision to Refuse Treatment;
- Decisions about Mental Health Act treatment (separate framework).
Deprivation of Liberty
Where a person without capacity is being cared for in a way that amounts to a deprivation of liberty (continuous supervision, not free to leave), legal authority is required:
- Deprivation of Liberty Safeguards (DoLS): in care homes and hospitals; managed by local authorities;
- Court of Protection orders: for community settings, supported living, and complex situations.
The DoLS framework was due to be replaced by Liberty Protection Safeguards but implementation has been deferred.
Independent Mental Capacity Advocate (IMCA)
An IMCA is a statutory advocate appointed where:
- A person lacks capacity for a serious decision;
- They have no family or friends to consult;
- The decision concerns serious medical treatment, change of residence, or specific Deprivation of Liberty cases.
IMCAs are free and provided by approved organisations under contract with local authorities.
Scotland and Northern Ireland
- Scotland: Adults with Incapacity (Scotland) Act 2000; similar principles, different formal structures.
- Northern Ireland: Mental Capacity Act (Northern Ireland) 2016; broadly aligned with the England and Wales Act.
Frequently asked questions
Can family overrule my decisions?
While you have capacity, no. Your family may disagree but cannot override your decisions. If capacity is later lost and there is no Lasting Power of Attorney for health and welfare, decisions are made in your best interests in consultation with family.
What is the difference between an unwise decision and lacking capacity?
An unwise decision is one that others may disagree with. Lacking capacity means the person cannot understand, retain, weigh or communicate the decision. The two are distinct; an unwise decision does not by itself imply lack of capacity.
Who decides whether I have capacity?
The person responsible for the decision (a clinician, a solicitor, a family member acting under an LPA). For complex or contested cases, a specialist clinician or the Court of Protection may be involved.
Can I refuse all future treatment now?
Yes, with a valid Advance Decision to Refuse Treatment. Specific treatments are refused in advance; this is binding under the Mental Capacity Act.
What happens if I lose capacity without an LPA?
Decisions are made in your best interests under the Act. Family may need to apply to the Court of Protection for a Deputyship to manage finances, which is slower and more costly than an LPA. This is why setting up an LPA early matters.
References
- Mental Capacity Act 2005 and Code of Practice.
- Adults with Incapacity (Scotland) Act 2000.
- Mental Capacity Act (Northern Ireland) 2016.
- Court of Protection. https://www.gov.uk/courts-tribunals/court-of-protection