Mental Capacity Act in the ICU

Contents

Overview

The Mental Capacity Act (MCA) 2005 is the legal framework governing decision-making for people who lack capacity to make their own decisions in England and Wales. It applies to anyone aged 16 and over. In the ICU, the MCA is relevant to almost every clinical encounter — from decisions about intubation in an acutely unwell patient, to withdrawal of life-sustaining treatment in a patient with prolonged disorders of consciousness. Understanding and applying the MCA is a core ICU competency. See also the article on Best Interests Decisions for the best interests framework.

The Five Principles

The MCA is built on five statutory principles, which must be applied in every decision made under the Act:

1. Presumption of capacity: Every adult must be assumed to have capacity unless it is established that they lack it. The burden of proof lies with the person asserting incapacity, not with the patient.

2. Supported decision-making: A person is not to be treated as unable to make a decision unless all practicable steps have been taken to help them do so without success. In the ICU, this means simplifying information, using communication aids, optimising the environment, and choosing the best time to have conversations.

3. Unwise decisions are permitted: A person cannot be treated as lacking capacity solely because they make a decision that others consider unwise. An adult with capacity has an absolute right to make unwise decisions — including refusing life-saving treatment.

4. Best interests: Any act done or decision made for a person who lacks capacity must be in their best interests.

5. Least restrictive option: Before acting, regard must be had to whether the purpose can be achieved in a less restrictive way. This applies to both freedom of action and freedom of decision.

Assessing Capacity

Capacity under the MCA is decision-specific and time-specific. A patient may have capacity for one decision (agreeing to a blood test) but not another (consenting to a complex surgical procedure). Capacity may fluctuate over time — for example, in delirium.

The Two-Stage Test

Stage 1 — Diagnostic threshold: Is there an impairment of, or disturbance in, the functioning of the mind or brain? This includes permanent conditions (dementia, learning disability) and temporary conditions (delirium, unconsciousness, intoxication, acute psychosis, pain, fear).

Stage 2 — Functional test: As a result of that impairment, can the person:

  • Understand the information relevant to the decision?
  • Retain it long enough to make the decision?
  • Use or weigh the information as part of the decision-making process?
  • Communicate their decision (by any means — including gesture, eye movement, or assistive technology)?

The person must be unable to do all four for capacity to be absent. Failing one test alone is insufficient.

Documentation

Capacity assessment must be documented in the medical notes: the decision being assessed, the information provided, the assessment process, and the conclusion with reasoning. The senior clinician responsible for the decision is the appropriate assessor.

Advance Decisions to Refuse Treatment

An advance decision to refuse treatment (ADRT, previously called an advance directive or living will) is a decision made by a person with capacity about refusing specific treatments in future situations where they may lack capacity. A valid and applicable ADRT is legally binding.

Validity and Applicability

An ADRT is valid if:

  • Made by a person aged 18 or over
  • Who had capacity at the time
  • Has not been withdrawn
  • Has not been superseded by a subsequently created LPA (with authority over the relevant decision)
  • The person has not done anything clearly inconsistent with it (e.g., expressed a different view)

An ADRT is applicable to the decision at hand if:

  • It is relevant to the specific treatment proposed
  • The circumstances in which the treatment is proposed match those anticipated in the ADRT
  • There is no reasonable ground to believe circumstances have arisen that were not anticipated and would have changed the decision

Life-Sustaining Treatment

An ADRT refusing life-sustaining treatment (e.g., mechanical ventilation, CPR, artificial nutrition) must be in writing, signed by the person, signed by a witness, and include an explicit statement that it applies even if life is at risk.

A verbal ADRT refusing treatment not involving life-sustaining measures is legally valid if made to a clinician and documented.

Clinical Practice

When an ADRT is presented in the ICU, the clinical team must check validity and applicability. If valid and applicable, the treatment must not be given even if the clinical team believes it is in the patient's clinical best interests. If there is genuine doubt about validity or applicability, treatment may be provided while the uncertainty is resolved — the court can be approached urgently.

Lasting Power of Attorney

A Lasting Power of Attorney (LPA) is a legal document in which a person (the donor) appoints one or more attorneys to make decisions on their behalf when they lack capacity. There are two types:

Property and Financial Affairs LPA: Can be used by the attorney while the donor has capacity (unless restricted) and after loss of capacity.

Health and Welfare LPA: Takes effect only when the donor lacks capacity. Can cover personal welfare decisions including, if specifically stated, decisions about life-sustaining treatment. This is the relevant LPA for ICU clinical decisions.

What a Health and Welfare LPA Can Authorise

If the LPA contains explicit authority over life-sustaining treatment, the attorney can consent to or refuse treatment on the donor's behalf when they lack capacity. If the LPA does not include this authority, the attorney cannot make decisions about life-sustaining treatment.

The attorney must act in the donor's best interests — they do not have an independent decision-making right to impose their own views. An attorney can be challenged at the Court of Protection if they are not acting in the donor's best interests.

Verification

An LPA must be registered with the Office of the Public Guardian (OPG) to be valid. Clinicians should ask to see the registered LPA document and verify it has been registered (it will have an OPG stamp). A document that has not been registered is not legally valid. The OPG can be contacted during office hours to verify registration.

Independent Mental Capacity Advocate

An Independent Mental Capacity Advocate (IMCA) is a statutory advocate appointed to represent and support people who lack capacity and have no appropriate person to consult. IMCAs are required (by MCA section 37) before:

  • Serious medical treatment
  • Provision of long-term accommodation

in patients who lack capacity and are "unbefriended" — with no family, friends, or other appropriate person available to be consulted.

Who Requires an IMCA

An IMCA is needed when:

  • The patient lacks capacity for the relevant decision
  • The decision involves serious medical treatment (treatment with significant risk, where there is a fine balance between benefit and burden, or where treatment is proposed to be withheld or withdrawn)
  • There is no appropriate person to consult — no family, no LPA, no Court-Appointed Deputy

The IMCA is not a decision-maker. They represent the patient's interests, gather relevant information, and provide a report to the clinical team. The decision remains with the responsible clinician, acting in best interests.

An IMCA referral should not delay urgent treatment — treatment can be given in an emergency without an IMCA, with referral made as soon as practicable.

The Court of Protection

The Court of Protection has jurisdiction over all decisions relating to people lacking capacity. It can:

  • Make declarations on the lawfulness of proposed treatment (or refusal)
  • Appoint a Deputy to make ongoing decisions on behalf of a person lacking capacity
  • Remove an attorney who is not acting in the donor's best interests
  • Make one-off decisions where specific authority is required

When to Approach the Court

The Court should be approached when:

  • There is genuine legal uncertainty about whether a proposed action is lawful
  • There is persistent, unresolvable conflict between the clinical team and family/attorney
  • The patient is in a prolonged disorder of consciousness and withdrawal of clinically assisted nutrition and hydration is being considered (An NHS Trust v Y [2018] — Court approval required)
  • The validity or applicability of an ADRT is genuinely uncertain and treatment urgency allows

The Court can issue emergency orders within hours. Applications should not be avoided due to misconceptions about delay. The NHS Trust's legal team can advise on urgent applications.

Deprivation of Liberty Safeguards

The Deprivation of Liberty Safeguards (DoLS) under the MCA provide a legal framework for authorising the deprivation of liberty of people who lack capacity in hospitals and care homes, where that deprivation is necessary and in their best interests.

A person in the ICU who lacks capacity and cannot leave freely may be deprived of their liberty. Under DoLS, the managing authority (the hospital) must apply to the supervisory body (the local authority) for a standard authorisation, or grant an urgent authorisation if the deprivation is required immediately.

In practice, DoLS applies more commonly to patients in longer-term settings. For ICU patients, brief deprivations (sedation for life-saving treatment) are generally justified under section 5 of the MCA (acts in connection with care or treatment) for the immediate purpose, with formal DoLS authorisation for prolonged situations.

The Mental Capacity (Amendment) Act 2019 introduced the Liberty Protection Safeguards (LPS) to replace DoLS — scheduled to come into force at a future date.

Practical Application in the ICU

Emergency treatment: When a patient presents in life-threatening emergency and cannot consent (unconscious, severely confused), treatment may be provided under section 5 MCA as an act in connection with care or treatment, if it is in their best interests and a belief on reasonable grounds exists that the person lacks capacity. Document the assessment promptly.

Elective treatment in patient lacking capacity: Follow the full best interests process: assess capacity, identify an LPA or consultees, consult those who know the patient's wishes, make and document the best interests decision.

Refusing treatment by a patient with capacity: A competent adult may refuse any medical treatment, including life-saving treatment. This right is absolute. Document the decision, the information provided, the capacity assessment, and the patient's decision clearly.

When a patient's capacity fluctuates: Assess capacity at the time the decision is required. If the patient has capacity at any point, engage with them directly. Document capacity assessments regularly.

Viva Questions

A patient is brought to the ICU unconscious following a drug overdose. Her husband presents an advance decision refusing intubation. How do you proceed?

I would take the ADRT seriously and immediately assess its validity and applicability. To be valid, the document must have been made when she had capacity, must not have been subsequently withdrawn, and must not have been superseded by a later LPA. If the ADRT refuses life-sustaining treatment, it must be in writing, signed by the patient and a witness, and must contain an explicit statement that it applies even if life is at risk. I would check the document carefully for all of these elements. I would also assess applicability: does the ADRT apply to intubation in this specific clinical situation, and did the patient anticipate circumstances like this? If the ADRT is clearly valid and applicable, I must respect it even if I believe intubation is in her clinical best interests — a valid and applicable ADRT is legally binding. If there is genuine doubt about validity or applicability, I may provide treatment while urgently seeking legal clarification, including approaching the Court of Protection if necessary. I would document everything carefully. I would also note that the husband's wishes do not override the ADRT — his role is as a consultee, not a decision-maker, unless he holds a registered Health and Welfare LPA with explicit life-sustaining treatment authority.

What is the difference between an attorney under an LPA and a next of kin? Which has legal authority in the ICU?

These are fundamentally different roles under English law. A next of kin — a family member, usually the nearest relative by relationship — has no legal authority to make healthcare decisions on behalf of an incapacitated adult. They are consultees: people whose views must be sought when making a best interests decision, because they can often speak to what the patient would have wanted. Their view is important but not determinative. An attorney holding a registered Health and Welfare LPA has legal authority to make healthcare decisions on behalf of the donor when the donor lacks capacity, within the scope of the LPA. If the LPA specifically grants authority over life-sustaining treatment, the attorney can consent to or refuse that treatment. The attorney must act in the donor's best interests — they cannot impose their own views — and can be challenged at the Court of Protection. In practice, many families do not have LPAs in place, and the clinical team retains the legal responsibility for making best interests decisions in consultation with appropriate people. It is important to explain this distinction sensitively to families who assume they have legal authority to "make decisions" for their relative.

A patient in your ICU has been in a vegetative state following cardiac arrest for four weeks. The family want to continue all treatment; your team believes withdrawal is appropriate. How do you proceed?

This is one of the most ethically and legally complex situations in ICU practice. I would start by ensuring the diagnosis is accurate — a prolonged disorder of consciousness (PDOC) following cardiac arrest requires specialist neurological assessment, ideally with MRI, EEG, and formal PDOC assessment tools (CRSR, GCS-R). I would ensure the family has had full prognostic information from the neurology team and that sufficient time has been allowed for assessment. Good communication is essential: multiple family meetings, honest prognostic information, and exploration of the patient's own previously expressed values and wishes. If, after exhaustive communication, the clinical team believes withdrawal of clinically assisted nutrition and hydration (CANH) is in the patient's best interests and the family disagrees, the team should seek a clinical ethics committee opinion. Following the Supreme Court ruling in An NHS Trust v Y [2018], Court of Protection approval is required before withdrawing CANH from a patient in a vegetative or minimally conscious state if there is disagreement — either from the family, or if there is any doubt about the patient's wishes or the clinical assessment. I would contact the Trust's legal team to initiate a Court of Protection application, ensuring the family understands this process is designed to protect the patient's rights.