Understanding Capacity - For First Responders
What the Law Requires, What It Does Not, and How It Plays Out in Real Life
Important: This article is educational guidance for responders. It is not legal advice. Always follow your organisation’s policy, governance framework and seek senior clinical or legal support where appropriate.
This article contains discussion around themes including self harm and suicidal ideation.
Capacity decisions rarely happen in calm rooms.
They happen in kitchens at 3am, on bridges, behind locked doors, with distressed relatives and sometimes with police already on scene. This is where responders feel exposed.
If you override autonomy unlawfully, you breach the law. If you walk away from someone who genuinely lacks capacity, you may leave them at serious risk. The margin for error can feel uncomfortably narrow.
Most mistakes do not happen because clinicians lack compassion. They happen because the legal structure is not applied properly under pressure. The Mental Capacity Act 2005 provides a clear framework, but in real life assessments often drift into instinct, assumption or risk management rather than structured reasoning.
This guide brings the framework back into focus. It explains what the Act actually requires, how the two stage test works in practice, what “understand” and “use or weigh” really mean, when restraint may be lawful and how organisational policy limits apply. It also clarifies the distinction between the Mental Capacity Act and the Mental Health Act, and explains how Gillick competence applies to young people.
If you would like a concise reminder of the two stage test and documentation principles, you can download our Capacity and Consent quick reference sheet.
Capacity assessment and consent are core clinical skills taught across our prehospital care programmes, including our FREC 3 courses, FREC 4 courses and the FREC 3 RPL route.
This guide is written for responders working in England and Wales.
Contents
1. The Mental Capacity Act 2005 - What It Is For?
The Mental Capacity Act 2005 (MCA) applies to people aged 16 and over in England and Wales. It is not a detention law and it is not a mental health law. It is a legal framework that guides how decisions are assessed when there is doubt about a person’s ability to make them.
At its core, the Act asks a single, focused question: can this person make this decision at this time?
Capacity is both decision specific and time specific. A person may have capacity to refuse a blood test but lack capacity to manage complex financial affairs. They may lack capacity during a hypoglycaemic episode and regain it once their blood glucose is corrected. The law recognises this fluctuation. It does not label people as globally incapable.
The Act does not ask whether a decision is sensible, safe or aligned with professional advice. It asks whether the person is able to understand the relevant information, retain it long enough to make a decision, use or weigh that information as part of their reasoning process, and communicate their choice by any means.
If those elements are present, the decision belongs to the patient, even if it carries risk.
Autonomy is not optional under the Act. The presumption of capacity is a legal requirement, not a professional courtesy (Mental Capacity Act 2005, s.1).
2. The Five Principles
The Mental Capacity Act is built on five statutory principles set out in section 1 of the Act. These principles are not guidance. They are legal requirements. Every capacity assessment sits on top of them.
The starting point is the presumption of capacity. A person must be assumed to have capacity unless it is established otherwise. That means doubt alone is not enough. Concern alone is not enough. Risk alone is not enough. You must be able to identify evidence of impairment before moving forward with a formal assessment.
The second principle requires that all practicable steps are taken to help the person make the decision themselves. In practice, this might mean simplifying language, reducing noise, treating pain, correcting hypoglycaemia, allowing time, or involving communication aids. Capacity is not assessed in a vacuum. Support comes first.
The third principle is often misunderstood. The Act makes it clear that a person is not to be treated as lacking capacity simply because they make an unwise decision. People are allowed to take risks. They are allowed to disagree with professional advice. The perception of poor judgement does not equal legal incapacity.
Only when capacity is genuinely absent does the fourth principle apply. Any act done on behalf of a person who lacks capacity must be done in their best interests. This requires consideration of their wishes, feelings, beliefs and values, as far as they can be known.
Finally, any intervention must be the least restrictive option available. Even where capacity is lacking, the response must interfere with autonomy as little as possible.
Best interests is not a shortcut. It is a safeguard that applies only after incapacity has been properly established.
3. The Two Stage Test
The two stage test is set out in sections 2 and 3 of the Mental Capacity Act 2005.
It is sequential.
You must start at Stage 1. You do not jump straight to Stage 2 because the situation feels risky.
Stage 1
Is there an impairment or disturbance in the functioning of the mind or brain?
This can be temporary or permanent.
In pre hospital care, this may include:
Hypoglycaemia
Hypoxia
Head injury
Delirium
Intoxication
Acute mental health crisis
Severe acute pain
Here is the safeguard that protects autonomy:
If there is no evidence of impairment, the assessment stops.
The person has capacity for that decision at that time.
You do not move to Stage 2.
Risk alone does not justify progressing further.
Your role then becomes to:
Provide clear information
Explain consequences
Check understanding
Support informed choice
Stage 2
Only applies if Stage 1 is satisfied.
Because of that impairment or disturbance, is the person unable to:
Understand the relevant information
Retain that information long enough to make the decision
Use or weigh that information as part of the decision making process
Communicate their decision by any means
All four elements must be considered.
Failure in any one limb may indicate lack of capacity.
If the person can do all four, they have capacity for that decision at that time.
Even if you disagree with it.
4. Understanding vs Using or Weighing
Where Most Assessments Go Wrong
Understanding and using or weighing are different cognitive functions. A patient may pass one and fail the other.
Understanding
To understand information, a person must grasp the basic facts relevant to the decision. This includes the nature of their condition, the intervention being proposed, and the main risks of both accepting and refusing treatment.
They do not need medical terminology. They do not need to repeat textbook explanations. They need to be able to explain the situation in their own words in a way that shows genuine comprehension.
You are not assessing intelligence. You are assessing whether the information has been understood in a meaningful way.
If a patient can accurately describe what might happen if they refuse treatment, that usually indicates understanding.
Using or Weighing
Using or weighing is about reasoning.
It asks a different question: can the person apply the information to themselves and balance the consequences in a rational way?
This is where nuance matters.
A person may understand that untreated sepsis can lead to organ failure, but still be unable to weigh that risk because of impaired reasoning due to delirium. A person may understand that a paracetamol overdose can cause liver failure, but deny that it applies to them because of distorted thinking.
To weigh information, the person must be able to:
Compare options
Consider consequences
Connect action with outcome
Reach a decision through an intact reasoning process
Disagreement with you is not incapacity.
Risk taking is not incapacity.
Minimising risk does not automatically equal incapacity.
Impaired reasoning caused by disturbance of the mind or brain is incapacity.
That distinction protects autonomy.
And it protects you.
5. Acting in Best Interests and the Limits of Restraint
If a person lacks capacity for a specific decision, Section 5 of the Mental Capacity Act provides legal protection for acts carried out in their best interests. This protection applies only where there is a reasonable belief that the person lacks capacity and that the action taken is necessary and proportionate.
Best interests is not a shortcut. It applies only after incapacity has been properly established through the two stage test. If capacity is present, best interests does not apply.
Section 6 of the Act places limits on restraint. Restraint is lawful only if it is necessary to prevent harm to the person and proportionate to the seriousness and likelihood of that harm. Both elements must be satisfied.
Necessity asks whether harm is likely without intervention. Proportionality asks whether the level of force or restriction matches that level of risk.
Immediate and Time Critical Situations
In pre-hospital care, some situations do not allow for a prolonged or detailed capacity conversation.
A patient may be:
Actively haemorrhaging
Peri-arrest
Severely hypoxic
Actively seizing
Unconscious
Rapidly deteriorating
The law does not require delay in order to complete a structured verbal assessment if doing so would expose the patient to serious harm.
What is required is a reasonable belief, based on the circumstances, that:
The person lacks capacity for that decision at that time, and
Immediate action is necessary to prevent serious harm.
If a patient is unconscious, capacity is absent.
If a patient is peri-arrest and unable to engage meaningfully, capacity is functionally absent.
If a patient is so physiologically compromised that reasoning cannot occur, capacity may be absent.
In genuinely time critical scenarios, life saving intervention may be justified without a prolonged discussion.
However, urgency does not remove the framework.
The reasoning must still exist, even if it happens quickly:
What is the impairment?
Why can they not engage?
What harm will occur if I delay?
Is my action necessary and proportionate?
The assessment may take seconds rather than minutes. But it must still be defensible.
Once the situation stabilises, capacity should be reassessed if appropriate.
However, legal permissibility does not automatically equal professional authority.
Many NHS trusts and ambulance services operate restrictive or no restraint policies for frontline clinicians. These policies reflect clinical governance, risk management and training boundaries. The Mental Capacity Act does not override organisational policy.
Responders must act within their training, their employer’s policy and their governance framework.
In some situations, the safest and most appropriate course of action may be escalation rather than physical intervention.
The question is not simply “Can I restrain under the Act?”
It is “Am I lawfully justified, professionally authorised and proportionate in doing so?”
6. Real World Case Studies
Case Study 1: The Confident Refuser
A 48-year-old male presented with central chest pain radiating to his left arm. He was alert, oriented and haemodynamically stable. Observations were within normal limits. There was no evidence of hypoxia, hypoglycaemia, head injury, intoxication or confusion.
He declined hospital conveyance.
Before progressing further, Stage 1 was considered.
Was there any impairment or disturbance in the functioning of the mind or brain?
There was no clinical evidence of impairment. He was engaging appropriately, answering questions coherently and demonstrating intact cognition.
Stage 1 was not met.
The assessment stopped there.
Even so, the conversation did not end.
We explained the potential for myocardial infarction, the risk of deterioration and the benefits of hospital assessment. He was able to repeat the risks back in his own words. He acknowledged the possibility of serious harm, including cardiac arrest. He accepted that risk and stated clearly that he did not wish to attend hospital at that time.
He was not confused. He was not minimising risk irrationally. He was making a decision we disagreed with.
Risk alone does not remove autonomy.
Capacity was present for that decision at that time.
The role of the clinician then became clear: document thoroughly, provide safety netting advice and ensure the patient knew how to seek help if symptoms worsened.
Case Study: Suspected Overdose Behind a Locked Door
Control advised that a patient had called stating they had taken an overdose of medication that could impair them.
On arrival at the address, there was no response to knocking. After several attempts, the patient came to the door but refused entry. He was verbally aggressive and threatened to set a large dog on us if we remained.
We could not safely enter the property.
We could not conduct observations.
We could not meaningfully engage in conversation.
Without engagement, we could not carry out a structured capacity assessment.
Suspicion of overdose does not automatically mean incapacity.
The Mental Capacity Act does not authorise forced entry in order to assess capacity.
At that point, the key question became one of lawful authority.
We had a credible report of overdose and potential self harm. We had limited information about timing, quantity or substance. We had no way to assess mental state or physiological compromise.
Police were requested.
Forced entry was carried out under police powers, not under the Mental Capacity Act.
By the time entry was made, the patient had exited the property through a third-floor window and fled the scene.
This case illustrates an important boundary:
Capacity cannot be assumed without assessment.
And the Mental Capacity Act does not create entry powers for responders.
Where engagement is impossible and risk is credible, escalation to agencies with statutory authority may be appropriate.
Case Study 3: The Coherent Paracetamol Overdose
We were dispatched at 2am on a Saturday morning.
Control advised that a woman had left a voicemail with her mental health team late on Friday afternoon stating she intended to take an intentional overdose of paracetamol. The team had been unable to recontact her and escalated to 999.
On arrival, she answered the door.
She appeared well perfused.
She was fully alert.
There was no respiratory distress.
No visible pain.
No slurred speech.
Pupils appeared normal.
She calmly informed us that she had taken between 50 and 100 paracetamol tablets.
We asked to come inside to talk and complete observations. She declined.
We asked whether we could conduct observations at the doorway and speak there. She agreed.
A full set of observations was completed and were within normal limits.
This was not a brief interaction.
We remained on scene for several hours.
We built rapport.
We revisited risk repeatedly.
We explained the mechanism of delayed liver failure.
We explained the limited treatment window for treatment.
We explained the possibility of irreversible harm and death.
She declined to discuss what had triggered the overdose, stating politely that she had spoken to many professionals and did not wish to revisit it.
When asked about her intention, she stated clearly that her intention had been to end her life.
She informed us that she had researched paracetamol toxicity.
She accurately described:
The delayed onset of symptoms
The time-critical nature of treatment
The point at which liver damage may become irreversible
She was calm. She was consistent. She was not erratic or disorganised. There was no evidence of intoxication or psychosis.
Applying the Two Stage Test
Stage 1 was satisfied due to the presence of a mental health concern.
Stage 2 was then assessed limb by limb.
Understanding
She was able to explain the medical risks in her own words, including delayed deterioration and potential fatal outcome.
Retaining
Her explanation remained consistent over several hours. She did not contradict herself or lose track of information discussed.
Using or Weighing
This was the most difficult limb.
She acknowledged the risks.
She did not deny them.
She did not demonstrate delusional thinking.
She connected action with consequence.
She stated that she understood the likely outcome and that her intention had been to die.
Intending to die is not the same as being unable to reason.
Her reasoning process was intact.
Communicating
She clearly and repeatedly refused hospital attendance.
Capacity was assessed in relation to the specific decision of refusing hospital treatment at that time.
The assessment was made at the material time and would have been revisited had her presentation changed.
This was not a rapid doorstep decision.
Escalation pathways were considered.
Police involvement and Mental Health Act considerations were explored.
Safeguarding duties were complied with.
Documentation was detailed.
Every instinct was to remove her from that situation.
But unwise does not equal incapacity.
The assessment must focus on the reasoning process, not the outcome.
Reflective Question
If her answers had become inconsistent, If she had become disorganised in her thinking, If she had been unable to connect consequence with action,
How would that have changed the assessment?
This is where structured reasoning protects both patient autonomy and professional integrity.
7. Mental Capacity Act vs Mental Health Act
Understanding the Difference
The Mental Capacity Act 2005 and the Mental Health Act 1983 (as amended by the Mental Health Act 2007) are separate legal frameworks. They are often confused in emergency settings, particularly where mental illness and risk of self harm intersect.
The Mental Capacity Act is concerned with decision making. It applies when there is doubt about whether a person can make a specific decision at a specific time. It focuses on the individual’s reasoning process. The question it asks is simple but precise: can this person make this decision now?
The Mental Health Act serves a different purpose. It provides statutory powers for the compulsory assessment and treatment of mental disorder where defined legal criteria are met. Its focus is not the reasoning process behind a particular decision, but whether the threshold for detention is satisfied.
Mental illness does not automatically remove capacity. A person may live with significant mental health difficulties and still retain the ability to understand, retain, use or weigh information. Equally, a person without any diagnosed mental disorder may lack capacity because of delirium, hypoxia, intoxication or metabolic disturbance. The presence of mental disorder and the absence of capacity are not the same test.
Confusion commonly arises where a patient expresses suicidal intent but presents as calm and coherent. Risk alone does not convert the Mental Capacity Act into a detention power. If capacity is present, the MCA does not authorise removal. If the legal criteria for detention under the Mental Health Act are met, that is a separate statutory pathway.
It is also important to be clear about powers. Sections 135 and 136 of the Mental Health Act are police powers. They allow removal to a place of safety in defined circumstances. They are not powers held by ambulance clinicians. The Mental Capacity Act does not grant forced entry powers.
Understanding which framework applies protects patient autonomy and protects professionals from acting outside their authority.
8. Children and Gillick Competence
The Mental Capacity Act applies to individuals aged 16 and over. For those under 16, the legal framework is different.
Capacity in children is assessed using the principle established in Gillick v West Norfolk and Wisbech Area Health Authority [1986]. This introduced what is commonly referred to as Gillick competence.
Gillick competence recognises that a child under 16 may be capable of consenting to medical treatment if they demonstrate sufficient maturity and understanding of what is proposed.
The assessment is functional, not age-based.
The question is whether the young person understands the nature and purpose of the treatment, the risks and consequences involved, and the available alternatives, including the option of doing nothing. They must also be able to apply that information to themselves in a meaningful way.
Like the Mental Capacity Act, Gillick competence is decision-specific. A young person may be competent to consent to one type of treatment but not another.
There is an important distinction between consent and refusal. A Gillick-competent child can consent to treatment. Refusal of life-saving treatment is more complex and may require parental responsibility or court involvement. In practice, that situation will usually require escalation beyond scene-level decision making.
Safeguarding responsibilities remain at all times. Competence does not remove the need to consider exploitation, coercion or risk of significant harm.
Case Study: A 15-Year-Old Requesting Confidential Help
We were called to a 15-year-old boy who had dialled 999.
On arrival, his mother stated she was unaware that he had made the call.
When spoken to privately, he disclosed that he had taken an intentional overdose of medication. He appeared regretful and stated that it had been a mistake. He wanted help. He wanted to attend hospital. He wanted to speak with a mental health professional.
He also stated clearly that he did not want his parents informed of the details and did not want them to travel in the ambulance.
The assessment focused on maturity and understanding.
He was able to explain:
What he had taken
The potential physical risks
Why hospital treatment was necessary
That he would require both medical and mental health assessment
He demonstrated understanding of the consequences and the need for treatment.
He was not confused, intoxicated or pressured.
His reasoning was coherent and consistent.
On that basis, he was assessed as Gillick competent for the decision to consent to hospital treatment.
His request for confidentiality was respected at that stage, in line with competence principles and professional guidance.
Safeguarding duties were complied with in accordance with statutory responsibilities and local policy.
9. Documentation
Good documentation does not simply record a conclusion.
It records reasoning.
If your assessment were reviewed weeks later by a senior clinician, a coroner or a court, it should be clear:
What impairment was considered
Which stage of the test was applied
What evidence supported your conclusion
That the decision was specific and time-based
Avoid vague statements such as “capacity intact” or “capacity absent” without explanation.
Your notes should demonstrate how you reached that position.
Example: Capacity Present
“Patient alert and oriented to person, place and time. No identifiable impairment of mind or brain. Engaging appropriately. Able to explain the nature of their condition and the risks of refusing conveyance, including potential deterioration. Acknowledges consequences and states clear, consistent decision to remain at home. Capacity present for this decision at this time.”
This example shows:
Stage 1 considered and not met
Understanding demonstrated
Weighing demonstrated
Decision-specific language
Time-specific language
Example: Capacity Lacking
“Patient confused secondary to hypoglycaemia. Disorientated to time and situation. Unable to explain consequences of refusing treatment despite repeated explanation. Reasoning impaired. Capacity lacking for this decision at the time of assessment. Best interests intervention required.”
This example shows:
Identifiable impairment
Functional deficit under Stage 2
Link between impairment and reasoning
Decision-specific conclusion
Documentation should be structured, factual and calm.
It should describe behaviour and reasoning, not label character.
Where intervention occurs, record:
Why delay would have caused harm
Why the action taken was necessary
Why it was proportionate
Clarity protects the patient.
Clarity protects you.
10. A Practical Decision-Making Tool: PLANE
Under pressure, structured thinking often collapses into instinct.
PLANE is a simple framework that can help restore discipline in fast-moving situations.
It stands for:
Proportionate
Legal
Accountable
Necessary
Ethical
It is not a replacement for the Mental Capacity Act. It is a way of checking that your actions remain aligned with it.
Proportionate: Is the level of intervention proportionate to the level of risk? Am I escalating appropriately, or am I overreaching?
Legal: Do I have lawful authority for what I am about to do? Am I relying on the correct framework, or am I blurring the Mental Capacity Act with the Mental Health Act?
Accountable: Could I justify this calmly to a senior clinician, a safeguarding lead or a court? Have I documented the reasoning clearly?
Necessary: Is this action required to prevent harm, or am I acting because I feel uncomfortable with risk?
Ethical: Does this respect autonomy where capacity is present? Am I balancing beneficence with respect for the individual’s rights?
PLANE is particularly useful in moments where instinct urges immediate action.
It forces a pause.
It brings reasoning back to the surface.
Used properly, it strengthens defensibility without slowing appropriate care.
11. Key Takeaways
The two stage test is sequential. If there is no identifiable impairment of mind or brain, the assessment stops. Risk alone does not justify moving to Stage 2.
Capacity is decision specific and time specific. A person may have capacity for one decision and lack it for another, and capacity can fluctuate.
An unwise decision is not evidence of incapacity. The focus is on the reasoning process, not whether you agree with the outcome.
Suicidal intent does not automatically remove capacity. The presence of mental illness and the absence of capacity are separate legal questions.
In time-critical situations, urgent intervention may be justified where there is a reasonable belief that capacity is absent and delay would cause serious harm. Urgency does not remove the need for structured reasoning.
Restraint must be necessary, proportionate and within your professional authority. The Mental Capacity Act does not override organisational policy or create detention powers.
Clear, structured documentation should record your reasoning, not just your conclusion. Defensible practice is transparent practice.
Capacity is not about agreement.
It is about whether reasoning is intact.
References
Department for Constitutional Affairs (2007) Mental Capacity Act 2005 Code of Practice. London: The Stationery Office. Available at: https://www.gov.uk/government/publications/mental-capacity-act-code-of-practice (Accessed: 19 February 2026).
Gillick v West Norfolk and Wisbech Area Health Authority [1986] AC 112 (HL).
Mental Capacity Act 2005. London: The Stationery Office. Available at: https://www.legislation.gov.uk/ukpga/2005/9/contents (Accessed: 19 February 2026).
Mental Health Act 1983 (as amended by the Mental Health Act 2007). London: The Stationery Office. Available at: https://www.legislation.gov.uk/ukpga/1983/20/contents (Accessed: 19 February 2026).
National Institute for Health and Care Excellence (2018) Decision-making and mental capacity (NG108). London: NICE. Available at: https://www.nice.org.uk/guidance/ng108 (Accessed: 19 February 2026).
National Institute for Health and Care Excellence (2022) Self-harm: assessment, management and preventing recurrence (NG225). London: NICE. Available at: https://www.nice.org.uk/guidance/ng225 (Accessed: 19 February 2026).
