The Police and Criminal Evidence Act 1984

The objective of this act is too ensure that the police can do their job whilst the rights of the individual are also protected, 'The aim of the Act and the Codes is to give the police the powers they need to prevent and investigate crime while providing workable and effective safeguards for the citizen'. It also has a bearing on how the police handle situations where people who may be mentally ill are involved.
 
The major parts of the act pertaining to mental health are;
 
Appropriate adult - if an officer believes, or is told, that a person has a mental disorder/handicap then that person is entitled to certain protections. One such protection is the appropriate adult, which is in addition to the statutory legal assistance. Except in certain instances where a professional may be of more help the priorities are:-
 

• A relative or guardian
• A mental health professional
• An capable adult unconnected with the police force

Information - certain statutory information must be given upon detention, except where the detainee cannot understand it, would become violent or needs urgent medical treatment. In those cases it must be given as soon as possible. The information consists of why they are being detained, what steps will occur, their legal rights especially to representation and a caution.
 
Treatment - if a detainee does not demonstrate sensibility or awareness they must be medically examined as soon as possible, even if they have made no request for medical treatment. In urgent cases, this may be facilitated by sending the detainee to hospital. It is illegal for any police officer to administer medication to a detainee. Detainees may self medicate but only where this has been authorised by the police surgeon, who may decide to attend.
 
Representation - in very exceptional circumstances, representation may be denied. This is extremely unlikely to be the case for mental health problems. Both legal assistance and the appropriate adult must be present during any interview, and at the provision/signature of any documents. The representation has a duty not only to act as an observer, but to advise, facilitate communication and to ensure the interview is fair and proper. Any person in police detention at a hospital may not be questioned without the agreement of a responsible doctor.
 
Searches - can only be carried out under reasonable suspicion. These grounds must be explained to the person before the search. The search must be carried out by a medical professional and, for mental health problems, be witnessed by an appropriate adult of the same gender. No others persons should be present, and the search should be carried out with proper regard to the sensitivity and vulnerability of the person. The detainee has no legal right to refuse the search providing it has been properly authorised.

This is a brief overview of the
Police and Criminal Evidence Act
If you require specific guidance,
then please seek expert assistance
 
Full details of the Police and Criminal Evidence Act 1984 can be found at
The Home Office website