Arrest vs detention

Arrest versus Detention

Arrest and detention are distinct stages in the custody process. An arrest is the act of depriving a person of their liberty. Detention is the formal decision to keep a person at the police station after they have been brought to the custody suite.

Side by side

	Arrest	Detention
Legal basis	Section 24 PACE (without warrant) or a warrant issued by a court	Section 37 PACE: custody officer must authorise detention where there are reasonable grounds to believe it is necessary
Who authorises	Any constable (or a citizen for an indictable offence)	The custody officer (sergeant or above) at the designated custody suite
When it begins	When the officer tells the person they are arrested or physically restrains them with that intention	When the custody officer formally authorises detention after the person arrives at the custody suite
Requirement to inform	Must be told they are under arrest, the reason, and cautioned as soon as practicable	Must be informed of their rights under PACE Code C, including right to legal advice and to have someone informed
Time limits	No specific time limit on the arrest itself, but the person must be taken to custody without unnecessary delay	Initial limit of 24 hours from the relevant time; extendable to 36 hours (superintendent) and 96 hours (magistrates)
Custody record	The arrest is the trigger for bringing a person to custody, but a custody record is not opened at this stage	A custody record must be opened at the start of detention and maintained throughout
Release	A person can be de-arrested before reaching the custody suite if grounds are no longer met	Release from custody may be on bail, released under investigation, or following charge

Which applies

An arrest is the mechanism by which a person is brought before the custody officer; detention is the formal custody officer decision that follows. A person who is arrested may not ultimately be detained if the custody officer is not satisfied that the grounds for detention are met. It is possible to be at a police station voluntarily (for a voluntary interview) without being either arrested or detained.

Last updated 24 September 2026