Mentally ill or mentally handicapped persons who are apprehended for alleged commission of crimes may be unfit to deal with the criminal justice system. They may be unable to participate in reasonable and comprehending dialogue with police officers and investigators and with private or publicly appointed lawyers for the purposes of defence. Inability may extend to standing trial and pleading innocent or guilty. The treatment of such persons varies significantly from country to country. The mentally ill or handicapped person may be forced to stand trial without any special assistance, or may be interned without trial in a psychiatric hospital from which release is a difficult and prolonged process. In some countries such as the UK, there is provision for medical and mental treatment before trial.
A recent case in the UK involved a mentally deficient youth being committed to prison for stealing a milk bottle.