In practice, Section 16 of the Police and Criminal Evidence Act 1984 (PACE) governs how a police
search warrant is executed in England and Wales. It is a statutory provision. Any constable may execute the warrant and may authorise other persons (for example, specialists) to accompany and assist in the search or in seizing material covered by the warrant.
Key
execution requirements include that the officer identifies themself, produces the warrant on request and provides or leaves a copy for the occupier. The search and any seizure must be confined to the premises and items described in the warrant, unless separate PACE seizure powers (such as sections 19–22) apply. Compliance with section 16 and PACE Code B safeguards is central to the lawfulness of the entry and search; breaches can found challenges to admissibility under section 78 PACE.
Jurisdictional note: Section 16 PACE applies only in England and Wales. Northern Ireland has substantially similar rules under the Police and Criminal Evidence (Northern Ireland) Order 1989 (Article 16). Scotland and Ireland use different statutory regimes for
warrants, so “section 16 PACE” is not used there, though the practical issues around execution and seizure are analogous.