Does one encompass the other? What circumstances enable each to be done lawfully? What are the implications of each one?
Arrest involves detention but not vice-versa
Arrest refers to the power of police (and others) to detain you in order to prevent or investigate a potential offence.
You are detained when your freedom of movement is curtailed. An arrest necessary includes detention but there are many other circumstances where detention is lawful. For example, you are lawfully detained:
- at a traffic stop
- while serving a sentence of imprisonment
- while on remand
- when part of a crowd that is prevented from leaving a certain area for policing or safety reasons
- while in school detention
- at a customs and immigration point
- while in immigration detention