The police have the powers under section 24 of the Police and Criminal Evidence Act 1984 (PACE) to arrest without warrant for arrestable offences; these section of PACE, like all the other sections has many subsections. I have found seven subsections to section 24, these subsections break down under what conditions that a police officer may arrest somebody without a warrant and what an arrestable offence is.
A police officers can arrest anyone without warrant for offences for which the sentence is fixed by law and to offences for which a person of 21 years of age or over (not previously convicted) may be sentenced to imprisonment for a term of five years...; and to the offences to which the words 'arrestable offence' applies.
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