Daly, R (on the application of) v The Commissioner of Police of the Metropolis & Anor

A search warrant properly obtained on reasonable grounds is not invalidated merely because later evidence suggests that information before the issuing court was mistaken. The availability of material mistake of fact as a ground of judicial review depends on the nature of the decision under challenge. The narrow approach applicable to decisions affecting future legal status cannot automatically be transferred to search-warrant cases. Police officers must act in good faith, make full and frank disclosure, identify potentially adverse material, and take reasonable steps to check that information is accurate, recent and not maliciously or irresponsibly supplied. Where those safeguards are observed, the warrant protects officers unless malice is proved.

The claimant challenged a warrant obtained by the Metropolitan Police under section 23 of the Misuse of Drugs Act 1971 and executed at her premises. The warrant was granted after evidence concerning thermal imagery, the smell of cannabis, blacked-out windows and other observations was placed before a district judge. The search found no drugs.

The claimant alleged that the information was mistaken, misleading and malicious, and sought judicial review as a precursor to civil proceedings. The central issues were whether a subsequently established mistake of fact could invalidate an otherwise properly obtained warrant and whether the evidence established malice or a failure of disclosure.

1. The application for judicial review was dismissed. The district judge had reasonable grounds for granting the warrant, and the warrant had been properly obtained.

2. A subsequently established material mistake of fact does not, without more, invalidate a search warrant that was properly obtained on the information available at the time. Extending the mistake-of-fact principle to search warrants would undermine the protection intended to be provided by a warrant whenever execution failed to reveal evidence supporting the original suspicion.

3. The principles in E v Secretary of State for the Home Department [2004] EWCA Civ 49 are context-sensitive. Although material mistake of fact causing unfairness may support judicial review in some circumstances, its availability depends on the nature of the decision before the court. The decision in E concerned a decision affecting future status and rights, rather than a warrant determined on reasonable grounds using the information then available. The approach could not simply be translated into criminal jurisprudence.

4. Search warrants are an exceptional and coercive power. They should be sought in good faith, for a statutory purpose, and only after reasonable checks. The police must provide full and frank disclosure, including material potentially adverse to the application, and must not materially mislead the issuing judge. The judge must subject the application to rigorous critical analysis and give reasons.

5. The evidence did not establish malice. The officers checked the identity of the premises, made enquiries about occupation, conducted a further inspection and passed on information which they reasonably accepted. Any dispute about curtains or window coverings was immaterial, and the competing thermal evidence did not demonstrate that the police account was false.