What is detention?
When the police believe that someone has committed a crime, they can detain that person in custody for up to twelve hours, which may in certain circumstances be extended by a further twelve hours. At the end of the respective period the police must release the suspect unless they believe they have sufficient evidence to arrest them. If they release the suspect without charging them, they may still carry on investigating the crime.

What happens when someone is arrested?
Someone can be arrested after being detained, or can be arrested straight away. For example, if the police have enough evidence that someone has committed a serious crime, they can be arrested, and taken straight to a police station.

Being arrested gives the police powers to take photographs of the person, as well as fingerprints and DNA samples. When someone has been arrested, the police will decide whether to keep them in custody until going to court the next day, or if they will be let out released on an Undertaking

Young offenders
Offenders who are over the Age of Criminal Responsibility but are under the age of 16 (or 18 if they are subject to a child supervision order) can still be arrested and detained, but the rules are slightly different from those described here, which are for an adult offender.

Further information about the Youth Justice System is available on this website.