A special complaints and discipline department of the police service concerned will record a complaint from a member of the public if the complaint alleges misconduct by a particular officer or officers. The department will then investigate the complaint, possibly under the supervision of one of the Members of the independent PCA.

Mandatory and voluntary supervision
Some complaints must by referred to the independent PCA for supervision of the investigation.

Mandatory referral
When the alleged conduct of an officer has resulted in death or serious injury to some other person, the case must be referred to the Authority (Police Act 1996 section 70).

Additionally, police must refer any allegations involving:
assault occasioning actual bodily harm;
an offence under section 1 of the Prevention of Corruption Act 1906; or
any serious arrestable offence, such as causing death by reckless driving.

Voluntary referral
Under section 71 of the Police Act 1996, chief police officers can voluntarily refer any matter for supervised investigation that they feel has sufficient ‘gravity’ or exceptional circumstances surrounding it for it to warrant criminal proceedings or formal action for misconduct.