Introduction
Respecting patient autonomy while ensuring safe and appropriate care lies at the heart of medical practice. A crucial component of this is understanding and applying the principles of the Mental Capacity Act (MCA) 2005. Knowing how to perform a mental capacity assessment UKMLA candidates need is not just a legal requirement but an ethical imperative, ensuring that decisions are made correctly for adults who may, temporarily or permanently, be unable to make specific decisions for themselves.
This guide provides a clear framework for understanding the MCA and conducting capacity assessments, tailored for the UKMLA. We will explore the five core principles, the two-stage functional test, the concept of best interests decisions, and how these apply in clinical scenarios frequently encountered in exams and practice. This builds on fundamental concepts covered in UKMLA Medical Ethics and Law: Your Essential 4-Pillar Guide.
Key Takeaways
Presumption of Capacity: Always start by assuming an adult (16+) has the capacity to make their own decisions unless proven otherwise.
Support Decision-Making: Before concluding someone lacks capacity, you must take all practicable steps to help them make the decision themselves.
Unwise Decisions ≠Lack of Capacity: A person should not be treated as lacking capacity simply because they make a decision others deem unwise or eccentric.
Best Interests: Any act done or decision made for a person lacking capacity must be done in their best interests.
Least Restrictive Option: Before acting, consider if the purpose can be achieved in a way that is less restrictive of the person’s rights and freedom of action.
Why Mental Capacity Assessment UKMLA Requires Proficiency
Understanding the MCA is not optional; it’s a legal framework governing decision-making for potentially vulnerable adults.
Legal and Ethical Imperative in UK Practice
The MCA provides a legal framework to empower and protect people who may lack capacity to make some decisions for themselves. Healthcare professionals have a duty to understand and apply the Act correctly to respect patient rights and avoid legal challenge. It underpins crucial aspects of care, from obtaining consent to making decisions about treatment and welfare.
UKMLA Relevance (AKT Scenarios, CPSA Stations on Consent/Decision-Making)
AKT: Questions may test your knowledge of the 5 core principles, the criteria for assessing capacity, the concept of best interests, or the validity of Advance Decisions.
CPSA: Capacity assessment is a common theme in stations involving consent for procedures, treatment decisions for confused patients (e.g., delirium, dementia), or managing patients refusing care. You may need to demonstrate the assessment process or discuss a best interests decision.
Understanding the Mental Capacity Act (MCA) 2005
This Act provides the legal structure for acting and making decisions on behalf of adults who lack the mental capacity to make particular decisions for themselves.
Scope and Purpose
The MCA aims to:
Empower individuals to make decisions for themselves where possible.
Protect vulnerable people who lack capacity by ensuring decisions are made in their best interests.
Provide clear legal rules for assessing capacity and making best interests decisions.
Allow people to plan ahead for a time when they might lack capacity (Advance Decisions, LPAs).
The definitive guide is the official statutory Mental Capacity Act: Code of Practice, which healthcare professionals have a legal duty to regard.
Who Does it Apply To?
The MCA applies to everyone aged 16 and over in England and Wales who may lack capacity to make decisions about their care, treatment, finances, or welfare. Note the age threshold – while 18 is the age of majority for many things, the MCA applies from 16 for healthcare decisions.
The 5 Statutory Principles of the MCA
These five principles are the foundation of the Act and must guide every assessment and decision.
Principle 1: Presumption of Capacity
Core Idea: Every adult (16+) has the right to make their own decisions and must be assumed to have capacity unless it is established that they lack capacity.
Implication: Do not assume lack of capacity based on age, appearance, condition, or behaviour. The burden of proof is on demonstrating lack of capacity.
Principle 2: Supporting Individuals to Make Decisions
Core Idea: A person must be given all practicable help before anyone treats them as not being able to make their own decisions.
Implication: This involves providing information in an accessible format (simple language, pictures, interpreters), choosing the best time and place, involving family/carers for support (if the person agrees), and breaking down complex decisions.
Principle 3: Right to Make Unwise Decisions
Core Idea: A person is not to be treated as unable to make a decision merely because they make an unwise decision.
Implication: Focus on the process of decision-making, not the outcome. If a person understands, retains, weighs, and communicates a decision (even if it seems risky or illogical to others), they have capacity to make it. Respect for autonomy includes respecting choices we disagree with.
Principle 4: Acting in Best Interests
Core Idea: An act done, or decision made, under this Act for or on behalf of a person who lacks capacity must be done, or made, in their best interests.
Implication: This applies only when capacity for the specific decision has been assessed and found lacking. It requires following a structured checklist (see below).
Principle 5: Least Restrictive Option
- Core Idea: Before the act is done, or the decision is made, regard must be had to whether the purpose for which it is needed can be as effectively achieved in a way that is less restrictive of the person’s rights and freedom of action.
- Implication: Always consider alternatives. If providing care at home with support is possible instead of hospital admission, or if observation is a reasonable alternative to sedation, the least restrictive option that still achieves the necessary aim should be chosen.
Table 1: The 5 Core Principles of the Mental Capacity Act
| Principle | Summary |
|---|---|
| 1. Presumption of Capacity | Assume capacity unless proven otherwise. |
| 2. Support Decision-Making | Provide all practicable help before assessing inability. |
| 3. Right to Unwise Decisions | An unwise choice does not automatically mean lack of capacity. |
| 4. Best Interests | Act/decide in best interests if capacity is lacking. |
| 5. Least Restrictive Option | Choose the option that least restricts rights and freedom. |
The Two-Stage Functional Test for Assessing Capacity
Capacity is decision-specific and time-specific. A person may have capacity for simple decisions but not complex ones, or capacity may fluctuate (e.g., delirium). The assessment must relate to the particular decision at the particular time it needs to be made.
Stage 1: Is there an Impairment or Disturbance?
Question: Does the person have an impairment of, or a disturbance in the functioning of, the mind or brain?
Examples: Dementia, delirium, significant learning disability, acute confusion (e.g., due to infection/metabolic disturbance), effects of drugs/alcohol, concussion, stroke, mental illness affecting decision-making.
Note: If there is NO impairment or disturbance, the person cannot lack capacity under the Act.
Stage 2: Is the Impairment Causing Inability to Make a Specific Decision?
Question: Does the impairment or disturbance mean the person is unable to make the specific decision at the time it needs to be made?
The Four Functional Tests: The person is unable to make the decision if they cannot do any one of the following:
Understand the relevant information?
Can the person comprehend the nature of the decision, the reasons for it, the likely consequences of deciding either way (including risks/benefits), and the consequences of making no decision? Information must be given in an accessible way (Principle 2).
Retain the information long enough?
Can the person hold onto the key pieces of information for long enough to actually engage in the decision-making process? (Memory impairment may affect this, but needing prompts doesn’t automatically mean inability to retain).
Use or Weigh the information?
Can the person engage in the process of considering the relevant information, appreciate its significance for them, and weigh the pros and cons to arrive at a choice? This is often the most complex part to assess.
Communicate the decision?
Can the person express their decision, whether by talking, using sign language, blinking, or any other means?
If the person fails on any one of these four points because of the impairment identified in Stage 1, they lack capacity for that specific decision at that time. Practical guidance for doctors is available from the BMA – Mental capacity in England and Wales.
Table 2: The 4 Functional Tests for Capacity
| Functional Test (Can the person…) | Key Aspect |
|---|---|
| 1. Understand | Comprehend relevant information (nature, purpose, risks, benefits, alternatives). |
| 2. Retain | Hold information long enough to make the decision. |
| 3. Use or Weigh | Consider the information, appreciate its relevance, balance pros/cons. |
| 4. Communicate | Express the decision (verbally, non-verbally). |
Making Decisions in the Patient’s Best Interests
If a person is assessed as lacking capacity for a specific decision, any action taken must be in their best interests (Principle 4). This requires a careful, holistic assessment.
The Best Interests Checklist (Key Factors to Consider)
The decision-maker must consider all relevant circumstances, including:
The person’s past and present wishes and feelings (especially any written statements).
The beliefs and values likely to influence their decision if they had capacity.
Other factors they would likely consider if able.
Views of family, carers, attorneys (LPA), or court-appointed deputies regarding what the person would want (though the final decision rests with the healthcare professional for treatment decisions, unless overruled by a valid ADRT or LPA).
Avoiding assumptions based on age, appearance, condition, or behaviour.
Considering whether the person might regain capacity (if so, can the decision wait?).
Involving Family and Carers
Consulting family/carers is crucial for understanding the person’s wishes, feelings, beliefs, and values. However, relatives do not have the right to consent or refuse treatment on behalf of an adult lacking capacity, unless they hold a valid Lasting Power of Attorney for Health and Welfare or are a court-appointed deputy.
Avoiding Discrimination
Decisions must not be made based on discriminatory assumptions about quality of life related to age or disability.
Advance Decisions and Lasting Power of Attorney (LPA)
The MCA allows individuals to plan ahead:
Advance Decision to Refuse Treatment (ADRT)
A legally binding refusal of specific medical treatment, made in advance by a person with capacity, intended to apply if they later lose capacity.
Must be valid (made by person 18+, with capacity, specifying treatment, clear about circumstances) and applicable (relevant to the current situation).
If refusing life-sustaining treatment, it must be in writing, signed, witnessed, and state clearly the refusal applies even if life is at risk.
An applicable and valid ADRT must be followed, even if doctors believe it’s not in the patient’s best interests. This is linked closely to informed consent guidelines.
Lasting Power of Attorney (LPA)
A legal document where a person (‘donor’) appoints one or more ‘attorneys’ to make decisions on their behalf if they lose capacity.
Two types: Health and Welfare, and Property and Financial Affairs.
A Health and Welfare LPA allows the attorney(s) to make decisions about treatment and care (including life-sustaining treatment, if specified).
If a valid LPA exists and applies to the decision, the attorney(s) legally make the decision, acting in the person’s best interests.
Documentation and Record Keeping
Thorough documentation is essential:
Record the specific decision being assessed.
Document the two-stage capacity assessment, including evidence for why the person is unable to undertake each relevant functional step (Understand, Retain, Weigh, Communicate).
Detail the steps taken to support decision-making (Principle 2).
If capacity is lacking, document the best interests decision-making process, including who was consulted and the factors considered.
Record details of any relevant ADRT or LPA.
Putting It All Together: 2 UKMLA-Style Clinical Scenarios
Case 1: Assessing Capacity for Consent to Surgery in a Patient with Dementia
Vignette: Mr. Lee, 80, has moderate Alzheimer’s dementia and requires surgery for a fractured hip after a fall. You need to obtain consent.
Assessment Approach:
Presume Capacity: Start assuming he can consent.
Support: Choose a quiet time, involve his daughter (with his agreement). Use simple language, diagrams. Explain the fracture, the proposed surgery (hip replacement/fixation), the risks (bleeding, infection, anaesthesia, confusion, immobility), benefits (pain relief, mobility), and alternatives (conservative management – likely poor outcome).
Two-Stage Test:
Stage 1: Impairment = Alzheimer’s dementia.
Stage 2 (Functional): Can he understand the basic information about the surgery, risks, benefits, alternatives? Can he retain it long enough to weigh it up (even with prompts)? Can he weigh the pros and cons in relation to his own situation? Can he communicate a choice?
Outcome: If he can do all four, he has capacity (even if he refuses). If he fails one because of his dementia (e.g., cannot retain key risks despite support), he lacks capacity for this decision now.
Action if Lacks Capacity: Check for ADRT/LPA. If none, proceed via a Best Interests decision involving the clinical team and consulting his daughter about his likely wishes/values. Document thoroughly.
Case 2: Best Interests Decision for NG Feeding in a Patient Post-Stroke
Vignette: Mrs. Jones, 75, had a severe stroke 2 weeks ago leaving her with dense hemiplegia and dysphagia, requiring NG feeding. She is now medically stable but minimally communicative (some eye contact, occasional nod). The team feels ongoing NG feeding is needed. She has no ADRT or LPA. Her son feels she “wouldn’t want this.”
Assessment Approach:
Capacity: Assume Mrs. Jones lacks capacity for this decision due to effects of stroke/communication difficulties (document assessment).
Best Interests: Apply the checklist.
Wishes/Feelings: Difficult to ascertain now, but consider past statements about quality of life if known.
Beliefs/Values: What was important to her? (Consult son).
Views of Others: Son feels she wouldn’t want NG feeding long-term. Why? What alternative does he suggest? What were her views on artificial nutrition?
Clinical Factors: Medical need for nutrition/hydration, potential benefits of NG feeding (recovery, rehab potential), burdens (discomfort, restraint?), prognosis with/without feeding.
Least Restrictive: Is PEG feeding an option/less restrictive long term? Is modified diet possible (SALT assessment crucial)? Is palliative approach more appropriate if prognosis very poor/burdens outweigh benefits?
Decision: Weigh all factors. If potential for recovery/rehab exists and burdens are manageable, continuing NG feeding may be in her best interests for now, with regular review. If prognosis is futile or burdens excessive, a palliative approach might be. Decision involves MDT discussion and careful communication with the son. Document rationale clearly. Issues around cognition also relate to High-Yield Psychiatry for UKMLA.
Sample Dialogue (Assessing Understanding):
“Mr. Lee, just to recap, the operation involves fixing your hip bone. The main benefit is to help the pain and allow you to walk again sooner. The main risks include bleeding during surgery, getting an infection, or potential problems with the anaesthetic like confusion afterwards. Can you tell me in your own words what the operation is for?” (Listen to response). “And can you tell me one of the main risks we discussed?” (Listen to response).
Frequently Asked Questions (FAQ) about Mental Capacity Assessment
No, absolutely not. Capacity is decision-specific and time-specific. A person with dementia may retain capacity for many decisions (e.g., what to wear, simple financial matters) while lacking capacity for more complex ones (e.g., consenting to major surgery, managing large sums of money). Capacity must be assessed individually for each significant decision, applying the two-stage functional test, and remembering the presumption of capacity (Principle 1).
Yes, very commonly. Capacity can fluctuate significantly. For example, a person may lack capacity during an episode of delirium due to infection but regain it once the infection is treated. Someone intoxicated with alcohol or drugs may lack capacity while intoxicated but regain it when sober. If a decision can safely wait until the person potentially regains capacity (e.g., treating delirium), it should be deferred.
The person responsible for making the decision or carrying out the action is responsible for assessing capacity for that decision. For day-to-day care decisions, this might be a nurse or carer. For treatment decisions, it is usually the healthcare professional proposing the treatment (e.g., the doctor consenting for surgery, the nurse administering medication). More complex cases may involve input from psychiatrists, geriatricians, or psychologists, but the principle remains with the decision-maker.
The MCA applies to people (16+) who lack capacity to make specific decisions due to an impairment or disturbance of the mind or brain, regardless of whether they have a mental health diagnosis. It covers decisions about treatment, care, finances etc. The MHA allows for compulsory assessment and treatment of people with a ‘mental disorder’ specifically for that mental disorder, even if they have capacity to refuse, if certain criteria regarding risk to self or others are met. The two Acts can sometimes apply concurrently but serve different primary purposes.
If an adult (16+) with capacity refuses treatment, their decision must be respected (Principle 3: Right to make unwise decisions), even if it seems illogical or could result in harm or death. The key is ensuring they do have capacity for that specific decision by applying the two-stage test: Do they have an impairment? Can they understand, retain, weigh, and communicate information about the proposed treatment, risks, benefits, and alternatives? If they can, their refusal is valid. If they lack capacity, treatment can be given if it’s deemed in their best interests (Principle 4).
Healthcare professionals are the final decision-makers for treatment decisions made in best interests (unless an attorney/deputy has authority). However, the views of family/carers about the person’s wishes, feelings, beliefs, and values are a crucial part of the best interests assessment and must be carefully considered. If significant disagreement persists that cannot be resolved through discussion, mediation, or seeking a second opinion, an application to the Court of Protection may be necessary to make a ruling.
This is complex. Under the MCA, a 16 or 17-year-old is presumed to have capacity like an adult. If they have capacity, their consent to treatment is valid. However, unlike adults (18+), their refusal of treatment (especially life-saving treatment) can potentially be overruled by someone with Parental Responsibility or by the Court, based on the principle of Gillick competence and the child’s best interests under the Children Act. Always seek senior/legal advice in such situations.
DoLS (soon to be replaced by Liberty Protection Safeguards – LPS) is an amendment to the MCA. It provides a legal framework to authorise the deprivation of liberty (i.e., continuous supervision and control, not free to leave) for people who lack capacity to consent to their care arrangements in hospitals or care homes, where such arrangements are necessary to protect them from harm and are in their best interests. It requires specific assessments and authorisations to ensure the deprivation is lawful.
Temporary intoxication due to alcohol or drugs can certainly cause a disturbance in the functioning of the mind or brain, potentially rendering someone unable to understand, retain, weigh, or communicate a decision (failing Stage 2). Capacity should be assessed based on their functional ability at the time the decision needs to be made. If the decision can wait until they are sober, it should be deferred. If urgent treatment is required while they lack capacity due to intoxication, it can be provided under the MCA if it is in their best interests.
The official Mental Capacity Act Code of Practice is the primary resource and provides detailed explanations and examples. Professional bodies like the BMA offer doctor-specific guidance. Educational resources from organisations like the Social Care Institute for Excellence (SCIE) also provide practical summaries and training materials.
Conclusion
Performing a mental capacity assessment UKMLA requires understanding both the legal principles of the Mental Capacity Act 2005 and the practical application of the two-stage functional test. Remembering the 5 core principles – especially the presumption of capacity and the need to support decision-making – ensures a patient-centred approach. When capacity for a specific decision is lacking, applying the best interests checklist in a structured way, considering the least restrictive option, and documenting clearly are essential.
This skill is fundamental to ethical practice and respecting patient autonomy. Regular practice in applying the principles and the functional test in clinical scenarios will build your confidence for the UKMLA and your future career.
Your Next Steps
Memorise the 5 Principles: Know these by heart as they underpin the entire Act.
Learn the 2-Stage Test: Understand the impairment/disturbance question and the four functional components (Understand, Retain, Weigh, Communicate).
Practice Application: Use clinical vignettes or real patient encounters (under supervision) to practice applying the two-stage test to specific decisions.
Understand Best Interests: Familiarise yourself with the factors to consider when making a best interests decision.
Review Key Resources: Refer back to the MCA Code of Practice and BMA guidance for authoritative details.
