The Mental Health Act of 1983 is a complex piece of legislation and covers many different areas, including compulsory admission to hospital, consent to treatment and the right of appeal, guardianship, and patients' involvement in criminal proceedings. There is also a separately published Code of Practice, which is regularly updated. This is a legally binding guide for doctors and social workers to operating the Act.

What follows here is a brief guide to the most commonly used sections of the Mental Health Act (2, 3, 4, 135 and 136). It is not therefore an authoritative statement of the law.

Most people who have mental health problems are treated in the community or in hospital on a voluntary basis and have the same rights as everyone else. They are sometimes called 'informal' patients. A small number of people are compulsorily detained under a section of the Mental Health Act 1983, and they have different rights. People who are compulsorily detained are referred to as 'formal' patients.

Grounds for Assessment
To be assessed for compulsory admission under the Act, the person must firstly be suffering from a mental disorder. This is defined by the Act to mean 'mental illness, arrested or incomplete development of mind, psychopathic disorder and any other disorder or disability of mind.'

Section 2: Assessment, 28 days
A person may be detained for assessment purposes for up to 28 days. The grounds for this are that the patient is: 'suffering from mental disorder of a nature or degree which warrants the detention of the patient in a hospital for assessment (or for assessment followed by medical treatment) for at least a limited period; and he ought to be so detained in the interests of his own health or safety, or with a view to the protection of other persons.'

Section 3: Treatment, 6 months
A person can be detained for treatment for up to six months (and this period can be renewed). The grounds for this are that the patient is: 'suffering from mental illness, severe mental impairment, psychopathic disorder or mental impairment and his mental disorder is of a nature or degree which makes it appropriate for him/her to receive medical treatment in hospital; and 'in the case of psychopathic disorder or mental impairment, such treatment is likely to alleviate or prevent a deterioration of his condition; and 'it is necessary for the health or safety of the patient or for the protection of other persons, that he should receive such treatment and it cannot be provided unless he is detained under this section.'

Procedure
With Sections Two and Three either an Approved Social Worker (ASW) or, if necessary and appropriate, a person's 'nearest relative' can make an application. This application must be supported by the recommendations of two registered medical practitioners. In addition, under Section Three the ASW must consult the 'nearest relative'. The application cannot proceed if the nearest relative objects, although court proceedings can be taken to overrule a nearest relative who objects unreasonably.
If a patient's nearest relative unreasonably objects to admission under Section 3, an application could be made to the County Court under Section 29 of the act for the functions of the nearest relative to be transferred to the local Social Services or another person.

Discharge
With both Sections, the patient may be discharged by any of the
following:
- Consultant Psychiatrist known as Responsible Medical Officer (RMO)
- The Hospital Managers
- The Nearest Relative - who must give 72 hours notice to the hospital managers, who in turn may overrule the request. The RMO can refuse the request on the grounds that discharge would be dangerous to the patient or to others. The nearest relative can then bring the case before a Mental Health Review Tribunal. The onus of proof is then on the RMO.

Appeals
The patient may appeal to the Mental Health Review Tribunal. Under Section Two this appeal must be made within 14 days of detention. Under Section Three one appeal can be made within the six month period. Patients may also appeal to the Hospital Managers. It is important to get advice about the wording of a letter to the managers and about representation at a managers' meeting or a Tribunal.

Section 4: Emergency, 72 Hours
A person may be detained for assessment purposes for up to 72 hours 'in any case of urgent necessity.' In this case the application is supported by the recommendation of one registered medical practitioner.

Section 5(2)
An informal or voluntary patient can be detained on a ward for up to 72 hours, by the doctor in charge of their treatment, or that doctor's nominated deputy if they think that by discharging him/herself, the patient is putting him/herself or others at risk. During the 72 hours the doctor will arrange for an assessment under Section 2 or 3 to be made. Detention under section 5(2) will end immediately, where:

Section 5:4
Gives the same power to a qualified nurse to detain on a ward someone already in hospital for up to 6 hours or until the arrival of a doctor with the power to use section 5(2). This holding power cannot be renewed once that time has elapsed.

Section 135 and Section 136
allow you to be taken by the police to a place of safety for assessment.
Under Section 135 an approved social worker can give evidence to a magistrate and obtain a warrant. This gives a police officer to power to enter premises where they think you are - they can break in if needed. The police officer must be accompanied by an approved social worker and a doctor. The grounds for the warrant are that it appears that:
You are being (or have been) ill-treated, neglected, or not kept "under proper control" or
That you are living alone and are unable to care for yourself.
If it is thought necessary you can be taken to a place of safety and held there for up to 72 hours to allow you to be assessed and for arrangements to be made for your treatment or care. This time limit cannot be extended.
Section 136 allows a police officer to take you to a place of safety if you are in a public place and it appears to the officer that you have a mental disorder and are in immediate need of care and control. If so you can be taken to a place of safety and held there for up to 72 hours. This is to allow you to be assessed by a doctor and an approved social worker, and any arrangements for your treatment or care to be made. The time limit cannot be extended.

A place of safety can be:
- A police station.
- A hospital.
- A mental nursing home or residential home for people with a mental disorder.
- A residential home provided by the social services.
- Any suitable place of which the occupier is willing to have you.

For an in depth guide to all aspects of the Mental Health Act:
Hyperguide to the Mental Health Act
or
The Mental Health Act
mental health law & related matters