The Mental Health Act at a glance
The Mental Health Act 1983 allows people with a mental disorder to be detained in hospital and, in some circumstances, treated without consent. Because it can deprive someone of their liberty without any crime, it has detailed safeguards, and courts expect them to be followed precisely. A detention that does not meet the legal requirements can breach Article 5 (the right to liberty) under the Human Rights Act 1998.
| Section | Purpose | Maximum length | Who is involved |
|---|---|---|---|
| Section 2 | Assessment (or assessment followed by treatment) | 28 days, not renewable | Application (usually by an AMHP) plus two medical recommendations |
| Section 3 | Treatment | 6 months, renewable for 6 months, then 12 months at a time | Application plus two medical recommendations; nearest relative consulted and can object |
| Section 4 | Emergency admission for assessment | 72 hours | Application plus one medical recommendation |
| Section 5(2) | Doctor's holding power for an inpatient | 72 hours | Doctor or approved clinician in charge of treatment, or nominated deputy |
| Section 5(4) | Nurse's holding power | 6 hours | Registered mental health or learning disability nurse |
| Section 136 | Police removal to, or keeping at, a place of safety | 24 hours (extendable by up to 12 hours in limited cases) | Police officer, after consulting a health professional where practicable |
Key terms you need to know
- Mental disorder: any disorder or disability of the mind. Dependence on alcohol or drugs alone is not a mental disorder under the Act. A learning disability only counts for longer-term sections such as section 3 if associated with abnormally aggressive or seriously irresponsible conduct.
- AMHP: an approved mental health professional, approved by a local authority to make applications and coordinate assessments.
- Section 12 approved doctor: a doctor approved as having special experience in diagnosing or treating mental disorder.
- Responsible clinician: the approved clinician with overall responsibility for a detained patient.
- Nearest relative: a person identified from a list in section 26, with specific legal rights. Not the same as next of kin.
The Code of Practice (2015) sets five guiding principles for every decision: least restrictive option and maximising independence; empowerment and involvement; respect and dignity; purpose and effectiveness; and efficiency and equity.
What is the difference between section 2 and section 3?
Section 2 is for assessment, often used when a person is not well known to services or their diagnosis or response to treatment is unclear. The test is that they have a mental disorder of a nature or degree that warrants detention for assessment for at least a limited period, and they ought to be detained for their own health or safety or to protect others. Treatment can be given under section 2 subject to the consent to treatment rules.
Section 3 is for treatment. The mental disorder must make it appropriate to receive treatment in hospital, treatment must be necessary for health, safety or protection of others and only possible if detained, and appropriate medical treatment must be available. The doctors must state where that treatment is available.
| Section 2 | Section 3 | |
|---|---|---|
| Length | Up to 28 days; cannot be renewed | Up to 6 months; renewable |
| Tribunal | Patient must apply within the first 14 days | Once in the first 6 months, then once in each renewal period |
| Nearest relative | Must be informed | Must be consulted; objection blocks the application unless displaced by a court |
| Section 117 aftercare | No | Yes, free aftercare after discharge |
Rules on applications and recommendations
- One of the two medical recommendations must be from a section 12 approved doctor.
- Where practicable, one doctor should have previous acquaintance with the patient; if neither does, the AMHP should record why.
- If the doctors examine separately, no more than five clear days may pass between the examinations.
- The applicant must have personally seen the patient within the 14 days ending on the date of application.
- Conflict of interest rules apply to doctors and applicants. Check the Regulations and Code if unsure.
When is section 4 used?
Section 4 is for urgent necessity: the criteria for section 2 are met, but waiting for a second doctor would cause undesirable delay. It needs an application and one medical recommendation, lasts up to 72 hours, and becomes a section 2 if a second medical recommendation is received in time. It should not be used just because a second doctor is inconvenient to find. Patients held only under section 4 are not covered by the Part 4 consent to treatment rules or entitled to an Independent Mental Health Advocate (IMHA), and section 17 leave is rarely appropriate.
Section 5(2) and 5(4): holding powers explained
Holding powers let staff hold an inpatient who is not already detained while an assessment for detention is arranged. They are often needed at night and weekends.
| Section 5(2) | Section 5(4) | |
|---|---|---|
| Who can use it | The doctor or approved clinician in charge of the patient's treatment, or their nominated deputy | A registered mental health nurse or registered learning disability nurse |
| Which patients | Any hospital inpatient, including on a general ward, not already detained | An inpatient already receiving treatment for mental disorder |
| Test | It appears an application for detention ought to be made | The patient needs to be immediately stopped from leaving for their health, safety or others' protection, and a doctor who can use 5(2) cannot attend immediately |
| Length | 72 hours | 6 hours, or until the doctor arrives if sooner |
| Form | H1, effective when furnished to the hospital managers | H2 |
- Section 5(2) cannot be used in the emergency department, because the patient is not yet an inpatient.
- A nominated deputy should be named under the hospital's arrangements and should not nominate someone else.
- If a doctor follows a 5(4) with a 5(2), the 72 hours run from when the 5(4) began.
- Neither power can be renewed. They should end when the assessment is done, not simply run out.
- Holding powers do not authorise treatment. Any treatment needs consent, or the Mental Capacity Act or common law.
Section 136 and section 135: police powers
Section 136 lets a police officer remove a person who appears to have a mental disorder and to be in immediate need of care or control to a place of safety, or keep them at one, if necessary in their interests or to protect others. It can be used anywhere except a private dwelling. The officer must consult a health professional first where practicable. Section 135 allows a magistrate to issue a warrant for police to enter premises and remove a person to a place of safety.
Since the Policing and Crime Act 2017, detention under sections 135 and 136 can last up to 24 hours, extendable by up to 12 hours in limited circumstances by the doctor responsible for the examination. A police station must not be used as a place of safety for under-18s, and for adults only in very limited circumstances set out in regulations.
Rights, treatment and the most common mistakes
Under section 132, detained patients must be told, orally and in writing and as soon as practicable, which section they are on, what it means and their rights, including applying to the Tribunal. Eligible patients must be told about IMHAs. The nearest relative can order discharge from section 2 or 3 with 72 hours' written notice, which the responsible clinician can block with a barring report if the patient would be likely to act dangerously.
For patients on sections 2 and 3, medication for mental disorder can be given for three months from first administration in the current detention; after that a T2 (consent certified) or T3 (SOAD certificate) is needed. Check the certificate covers the exact medicine and route before giving it.
| Common error | How to avoid it |
|---|---|
| Recommendations more than five clear days apart | Count clear days carefully |
| Section 5(2) used by a doctor who is not the nominated deputy | Know your hospital's nomination arrangements before nights and weekends |
| Treatment given "under the section" to a patient on a holding power | Holding powers do not authorise treatment; use the correct framework and record it |
| Medicine or route not covered by T2 or T3 | Keep certificates with the drug chart and check before prescribing and giving |
| Rights not given or not recorded | Give rights promptly, record understanding and repeat |
I completed a section 5(2) because he was trying to leave and was at risk. Nobody told me I had to be nominated. The nurse gave the medication. He was assessed the next day so no harm was done.
I used section 5(2) on a general ward overnight without checking I was the nominated deputy, so the patient was held without clear legal authority. I also did not make clear that holding powers do not authorise treatment, so intramuscular medication was given without assessing and recording whether it was justified under the Mental Capacity Act. I told the Mental Health Act office and my consultant as soon as I knew, and the patient was informed and assessed promptly. I have since read the Code chapter on holding powers and our nominated deputy policy, attended local Mental Health Act training, and now use a night checklist: confirm legal status, confirm I am the nominated deputy, complete and furnish Form H1, arrange assessment and record the legal basis for any treatment.
If you think a detention may be unlawful, tell the Mental Health Act office and responsible clinician at once, do not alter submitted forms, be open with the patient and report it. Some errors can be rectified under section 15 within 14 days of admission; fundamental defects cannot. If you are worried about your own role, seek early advice from your defence organisation, trade union or professional body.
Learning more about the Mental Health Act
Our course Mental Health Act 1983: Lawful and Safe Practice covers the detention sections, holding powers, section 17 leave, consent to treatment, patients' rights and paperwork, with worked examples and a reflection. Readers working in maternity or ambulance services may also find Maternity Care and Fetal Monitoring Concerns or Paramedic Practice: Assessment and Non-Conveyance Decisions useful. This guide is general information, not legal advice; follow your Mental Health Act office's advice and current guidance.
Frequently asked questions
How long can you be sectioned for?
It depends on the section. Section 2 lasts up to 28 days and cannot be renewed. Section 3 lasts up to six months, can be renewed for another six months and then for up to 12 months at a time. Section 4 lasts 72 hours. Patients can be discharged earlier by the responsible clinician, hospital managers or a Tribunal.
Can a nurse section someone?
A nurse cannot make an application for section 2 or 3; that is usually done by an approved mental health professional, who may be a nurse with AMHP approval. A registered mental health or learning disability nurse can use the section 5(4) holding power for up to six hours to stop an inpatient leaving while a doctor is called.
Can section 5(2) be used in A&E?
No. Section 5(2) only applies to hospital inpatients, and a patient in the emergency department has not been admitted. If someone in A&E needs to be prevented from leaving and is not detained under another power, the Mental Capacity Act or common law may apply. Seek senior advice and follow local policy.
Can you refuse medication on a section 2?
Patients on section 2 or 3 can be given medication for mental disorder without consent for the first three months, subject to the Code's safeguards. After three months, a T2 or a second opinion doctor's T3 certificate is needed. Treatment for unrelated physical conditions needs consent or must be given under the Mental Capacity Act.
What happens after a section 136?
The person is assessed at the place of safety by a doctor, ideally a section 12 approved doctor, and an AMHP. They may be admitted informally, detained under section 2 or 3, or discharged with support. Detention under section 136 lasts up to 24 hours, extendable by up to 12 hours in limited circumstances.
Has the Mental Health Act 2025 replaced the nearest relative?
The Mental Health Act 2025 will replace the nearest relative with a nominated person chosen by the patient, but this applies only once the relevant provisions are commenced. When this article was written, that had not happened and the nearest relative rules still applied. Check the current commencement position with your Mental Health Act office.
Can a person on section 3 have leave?
Yes. The responsible clinician can grant section 17 leave, with conditions such as escorted or unescorted, where and how long. Only the responsible clinician (or an approved clinician acting in that role) can grant it. For leave over seven consecutive days, they must consider a community treatment order instead.
Related courses
Mental Health Act 1983: Lawful and Safe Practice
This course gives doctors and nurses in England a practical understanding of the Mental Health Act 1983 as it applies on the ward and in emergency…
Maternity Care and Fetal Monitoring Concerns
This course teaches safe fetal monitoring in labour, including intermittent auscultation, structured CTG review and escalation, using UK guidance and…
Paramedic Practice: Assessment and Non-Conveyance Decisions
This course teaches a structured approach to assessment and safe decision-making when a paramedic considers discharging a patient on scene or…
Sources and further reading
- Mental Health Act 1983. legislation.gov.uk.
- Mental Health Act 1983: Code of Practice (2015). Department of Health.
- Reference Guide to the Mental Health Act 1983. Department of Health.
- Mental Health Act 2025. legislation.gov.uk.
- Guidance for the implementation of changes to police powers and places of safety provisions in the Mental Health Act 1983. Department of Health and Home Office.
- Monitoring the Mental Health Act. Care Quality Commission.
Practitioner Insight is an independent education provider. It is not affiliated with or endorsed by the GMC, MPTS, NMC, HCPC, GPhC or any NHS organisation, and this information is not legal advice. If you have been referred to a regulator, speak to your defence organisation, trade union or legal representative.
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