Police Powers, Arrest, Detention and Access to Legal Advice
Core framework
PACE 1984 supplies the architecture. Stop and search under s.1 requires reasonable grounds to suspect possession of stolen or prohibited articles; suspicionless powers are exceptional and must be expressly authorised. Arrest under s.24 requires reasonable grounds to suspect involvement in an offence plus the necessity criteria in s.24(4): to ascertain identity, prevent injury or damage, protect a vulnerable person, allow prompt investigation, or prevent prosecution being hindered. Necessity is assessed separately; lawful suspicion alone is not enough.
Detention and rights
A custody officer authorises detention under s.37. Reviews are conducted by an inspector at six hours and then at nine-hourly intervals. Detention expires at 24 hours unless a superintendent extends it to 36 hours for an indictable offence; a magistrates' court may extend to 96 hours. The suspect must be cautioned, informed of rights, and given s.56 intimation and s.58 legal advice. Delay of legal advice is rare, requires superintendent authorisation for an indictable offence, and must be justified.
Traps
Questions often confuse lawful arrest with necessity, or assume a suspect must answer questions. Voluntary attendance is not detention. The review officer must be independent of the investigation. Vulnerable suspects need an appropriate adult; absence can render evidence unreliable. A solicitor's presence is not a mere courtesy.
Rule of thumb
Ask: suspicion, necessity, lawful detention, rights, and review. If any element fails, consider s.78 exclusion.