You can be placed under this section if there is a reasonable cause to suspect that you have a mental disorder and you are:
being ill-treated or neglected or not kept under proper control, or
unable to care for yourself and live alone.
A magistrate can issue a warrant authorising a police officer (with a doctor and an approved mental health professional) to enter any premises where you are believed to be and take you to (or keep you are) a place of safety. You can be kept in hospital for up to 24 hours (this cam be extended up tp 36 hours in some circumstances).