Preliminaries to Prosecution and Investigation
Powers and necessity
Preliminaries span the period from suspicion to first appearance: police powers under PACE 1984 and the Codes of Practice, the charge decision, and the time limits governing the institution of proceedings.
Section 24 PACE permits arrest without warrant for any offence where there are reasonable grounds to suspect involvement, but only if the constable is satisfied that arrest is necessary for one of the five s.24(5) reasons: to ascertain a name or address, to prevent physical injury or damage to property, to protect a child or vulnerable person, to allow the prompt and effective investigation of the offence, or to prevent the prosecution being hindered by the suspect's disappearance. Necessity is a genuine additional hurdle; Code G requires the officer to consider whether a summons or voluntary attendance would suffice.
Detention and rights
The custody officer (s.37) may authorise detention only where necessary to secure or preserve evidence or obtain it by questioning. Reviews take place not later than six hours after detention is authorised and thereafter at intervals of no more than nine hours (s.40). The maximum before charge is 24 hours, extendable to 36 by a superintendent (s.42) and to 96 by the magistrates (s.43) for indictable offences. Key rights: s.56 (someone informed of arrest), s.58 (legal advice, delay only in narrow indictable circumstances authorised by a superintendent), Code C safeguards, and an appropriate adult for juveniles and mentally vulnerable suspects.
Charging and time limits
The Code for Crown Prosecutors' Full Code Test (evidential sufficiency, then public interest) governs charging; the Threshold Test applies where custody is sought before the evidence is complete. Summary-only proceedings must begin within six months of the offence (s.127 MCA 1980); either-way offences have no such limit, though delay may found an abuse of process argument.
Trap: reciting the s.24(5) reasons as a checklist rather than applying them. Rule of thumb: if the only stated reason is the seriousness of the offence or that the suspect 'would be arrested anyway', the arrest is unlawful and admissions may be challenged under s.78.