The Mental Capacity Act 2005 in Everyday Practice

Practice guides · Published 16 August 2026 · Last updated 16 August 2026

The Mental Capacity Act 2005 (MCA) applies in England and Wales to everyone aged 16 and over. If you support adults who may have difficulty making some decisions, whether because of dementia, a learning disability, a brain injury or a mental health condition, the MCA is not background law. It is the framework for how you offer a cup of tea, hand over medication, help someone shop and respond when a person makes a choice you would not make yourself.

The five principles

Section 1 of the Act sets out five principles. Every decision you support or make on someone's behalf must follow them, in order.

1. A presumption of capacity. You must assume a person has capacity to make a decision unless it is established that they lack it. A diagnosis is never proof of incapacity.
2. Support to make decisions. A person must not be treated as unable to decide until all practicable steps to help them have been taken without success. That means the right time of day, the right format, the right communication aids and enough time.
3. The right to make unwise decisions. A person is not to be treated as lacking capacity merely because they make a decision others think is unwise. Capacity is about the process of deciding, not the outcome.
4. Best interests. Any act done or decision made for a person who lacks capacity must be done in their best interests, following the checklist in section 4 of the Act.
5. The least restrictive option. Before acting, consider whether the purpose can be achieved in a way that interferes less with the person's rights and freedom of action.

Capacity is decision-specific and time-specific

Under sections 2 and 3 of the Act, a person lacks capacity for a particular decision at a particular time if they have an impairment or disturbance of the mind or brain, and because of that they cannot do one or more of the following: understand the relevant information, retain it long enough to decide, use or weigh it as part of the decision, or communicate their decision by any means.

This matters on shift because capacity fluctuates. Someone may be able to choose their lunch but not manage a tenancy agreement. Someone living with dementia may weigh a decision well at 10am and struggle at 6pm. You assess the decision in front of you, at the time it needs to be made, and you record what you saw, not just a conclusion.

Worked example: meals

Margaret, who has vascular dementia, refuses her pureed diet and asks for toast, despite a speech and language therapy recommendation because of swallowing risk.

Applying the principles: start by presuming she can make this choice. Support the decision, so explain the choking risk simply, at a calm moment, perhaps showing her the options. If she understands the risk, can hold onto it, weighs it against her strong preference for toast and tells you she still wants toast, she has capacity for this decision, and it is an unwise decision she is entitled to make. You would record the conversation, tell the manager, and look at ways to reduce risk she will accept, such as supervision while eating or a modified texture she finds acceptable. If she cannot understand or retain the risk information despite your best efforts, a best-interests decision is needed, and even then her wishes and feelings carry real weight in the section 4 checklist. The answer is rarely simply overriding her; it may be involving family, the SALT team and finding the least restrictive workable option.

Worked example: medication

David refuses his evening antipsychotic. Refusal is not, by itself, evidence he lacks capacity. Ask what is behind it: side effects, the taste, a belief he no longer needs it. Offer information in a form he can use. If he has capacity for this decision, you cannot force or hide medication; you record the refusal, monitor and escalate to the prescriber.

Covert medication, which means disguising medicine in food or drink, is only ever lawful for a person who lacks capacity for that decision, following a documented best-interests process involving the prescriber, pharmacist and those close to the person, with a written plan that is reviewed regularly. Slipping medication into tea because it is quicker is unlawful and a safeguarding matter.

Worked example: finances

Joan wants to give her nephew two hundred pounds from her personal allowance. Staff feel uneasy because he visits rarely and only asks for money. The unwise-decision principle applies: if Joan understands what she has, what she is giving, and the effect on her, it is her money. Discomfort is not a legal basis to stop her. But financial abuse is a genuine safeguarding category under the Care Act 2014, so if there are signs of pressure, coercion or a pattern of exploitation, raise a safeguarding concern; capacity to make a decision does not remove the duty to protect people from coercion. Check also whether anyone holds a registered Lasting Power of Attorney for property and affairs, or whether the Court of Protection has appointed a deputy, because that changes who can lawfully make which decisions.

Worked example: relationships

Two residents begin a relationship and staff worry about consent. Capacity to consent to sexual relations is decision-specific and the threshold of information is not high, but a person must be able to understand and weigh the relevant information, including the other person's ability to consent. If both have capacity, they have the same right to a private life as anyone else, under Article 8 of the European Convention on Human Rights, and the service should support privacy and dignity. If there is genuine doubt about either person's capacity, do not improvise: record concerns factually, involve the manager, and seek advice, because a person who lacks capacity cannot consent and others cannot consent on their behalf.

Best interests and restriction

When a best-interests decision is needed, section 4 requires you to consider the person's past and present wishes, feelings, beliefs and values, consult those close to them and anyone with legal authority, involve the person as far as possible, and not make assumptions based on age, appearance or condition. Choose the least restrictive option that meets the need. If the arrangements amount to a deprivation of liberty, meaning the person is under continuous supervision and control and is not free to leave, and they lack capacity to consent to those arrangements, an authorisation is needed under the Deprivation of Liberty Safeguards. Restriction without authorisation is not a paperwork problem; it is a human rights problem.

Recording

Good MCA practice lives or dies in the records. Write down the decision in question, the support you offered, what the person said and did, your assessment against the four functional abilities, who you consulted and why the chosen option was the least restrictive. A record that says only that a person lacks capacity will not stand up to scrutiny from CQC, a safeguarding enquiry or the Court of Protection.

Dos and don'ts

Dos

• Presume capacity for every decision, every time, whatever the diagnosis.
• Assess capacity for the specific decision at the specific time it arises.
• Take all practicable steps to support the decision before concluding anyone lacks capacity: timing, communication aids, familiar people, plain language.
• Respect unwise decisions made with capacity, and manage risk around them.
• Use the section 4 best-interests checklist and consult family, advocates and attorneys or deputies.
• Record what you observed, what you tried and how you reached your conclusion.
• Raise a safeguarding concern where you suspect coercion or abuse, even if the person appears to have capacity.

Don'ts

• Don't treat a diagnosis, age or appearance as evidence of incapacity.
• Don't label a decision as lacking capacity just because it is risky or inconvenient.
• Don't give medication covertly without a documented best-interests process involving the prescriber.
• Don't apply one capacity assessment to every decision or assume it lasts forever.
• Don't restrict someone's freedom without considering less restrictive options and, where needed, lawful authorisation.
• Don't record bare conclusions without the evidence and reasoning behind them.