Section 136 of the Mental Health Act is a section which allows the Police in England & Wales to detain somebody in a public place who appears to be mentally disordered as is in need of immediate care and/or control - this includes suicide attempts. Once such a person is apprehended, he or she is taken to a 'Place of Safety' which is:
2. Section 136 Suite
3. A Police Station
Theoretically, police stations should only be used in exceptional circumstances, but the reality is they are used very often, even when unneeded due to the fact most police officers aren't trained in Mental Health.
A s136 is not a criminal record, despite police detention, however it can be disclosed to potential employers if it's neccessary in an enhanced CRB check, which is considered by many to be unfair.
Typical use of a Section 136:
Aaron is an 19 year old student who became massively distressed after his girlfriend of two years left him, he decided he would throw himself off a bridge, however, luckily the police were able to talk him down and detained him under a 136 so his mental health could be assessed, he was then sent voluntarily to a psychiatric ward for treatment.
Other uses of 136:
Becky is a 20 year old female suffering from bipolar depression, during a night out with her friends she suffered a massive manic episode as she forgot to take her medication, and the police detained her under 136. She was then assessed and sectioned in a psychiatric ward for more treatment.