Crown Prosecution Service, R (on the application of) v Wolverhampton Magistrates' Court

Evidence obtained after an unlawful arrest is not automatically excluded. Under section 78 of the Police and Criminal Evidence Act 1984, the question is whether admitting the evidence would adversely affect the fairness of the proceedings to such an extent that it ought not be admitted.

The power cannot be used as a sanction for inadequate police training or resources where the arrest caused no unfairness in the trial. A general power of arrest should also not be used to circumvent a specific statutory precondition governing arrest for a road traffic offence.

The Crown Prosecution Service sought judicial review of the Wolverhampton Magistrates' Court's decision to uphold a submission of no case to answer on a charge of driving with excess alcohol under section 5 of the Road Traffic Act 1988.

The arrest followed the failure of a police officer to administer a preliminary roadside breath or impairment test. The District Judge held the arrest unlawful and excluded the subsequent station breath-test and blood-alcohol evidence under section 78 of the Police and Criminal Evidence Act 1984. The central issue was whether the evidence should have been excluded because of the unlawful arrest and the police force's failure to train the officer.

1. The application was granted. The acquittal was quashed and the case was directed to return to the Magistrates' Court for the trial to continue before the same District Judge.

2. The court treated the real issue as the application of section 78 of the Police and Criminal Evidence Act 1984. The statutory question was whether admitting the evidence would have such an adverse effect on the fairness of the proceedings that it ought not to be admitted.

3. The District Judge had not applied that test. He had instead excluded the evidence as a response to the police force's inadequate implementation and training concerning the new roadside testing provisions in sections 6A to 6D of the Road Traffic Act 1988. That approach turned section 78 into a sanction against the police rather than an assessment of trial fairness.

4. Even assuming that the absence of a preliminary roadside test made the arrest unlawful, it caused no unfairness to the defendant. The station readings made it inconceivable that a roadside test would have produced a favourable result. In any event, an officer who had reasonable cause to suspect a section 4 offence remained entitled to arrest.

5. The court accepted that inadequate police training was regrettable, but held that the remedy did not lie in excluding reliable evidence under section 78. Mr Justice Ouseley added that the general arrest power in section 24 of the Police and Criminal Evidence Act 1984 should not be used to circumvent the specific statutory precondition in section 6D of the Road Traffic Act 1988.

• High Court (Administrative Court): Permission for judicial review was granted on 27 March 2009. The court subsequently granted the claim, quashed the acquittal and remitted the case to the Magistrates' Court for trial before the same District Judge.