The Director of Public Prosecutions, R (on the application of) v Preston

The discretion under section 78 of the Police and Criminal Evidence Act 1984 must be exercised on an evidential basis. A breach of the Codes of Practice does not by itself justify excluding reliable evidence. Where a court relies on a detainee’s alleged failure to comprehend a procedure, that conclusion must be supported by evidence. A decision to exclude evidence is Wednesbury unreasonable where there is no evidence of a material breach or of the alleged failure of comprehension. The proper course is ordinarily to quash the decision and remit the matter for rehearing, rather than direct a conviction.

The Director of Public Prosecutions appealed by case stated against the dismissal of a charge under section 5(1)(a) of the Road Traffic Act 1988. The magistrates had excluded the respondent’s blood-alcohol analysis under section 78 of the Police and Criminal Evidence Act 1984, finding breaches of Code C and concluding that he had not comprehended the drink-drive procedure. The central issues were whether those findings had an evidential basis and whether exclusion of the analysis was lawfully open to the magistrates.

1. The appeal succeeded. The magistrates’ decision to exclude the blood-alcohol analysis was Wednesbury unreasonable because the case stated disclosed no evidence justifying a material, substantial or significant breach of Code C, or the conclusion that the respondent did not comprehend the drink-drive procedure.
2. There was no evidential basis for finding a breach of Code C paragraph 1.4. The respondent’s history of manic depression did not establish that he was mentally incapable of understanding questions or replies, nor was there evidence that the custody sergeant suspected that this was so.
3. Even if an appropriate adult should have attended, that breach alone would not necessarily justify exclusion under section 78. The court adopted the approach in Evans (CO/291O/2002), that the statutory drink-drive procedure should not ordinarily be delayed and that exclusion must be justified by the circumstances and the issues arising.
4. A breach of paragraph 9.2 could be established if no doctor had been called, since the respondent appeared to suffer from physical illness. However, the doctor attended and took the blood specimen shortly afterwards. Any breach could not properly be characterised as substantial and significant.
5. There was no evidence warranting a finding of a breach of paragraph 9.6, still less a serious breach. The magistrates’ reliance on the respondent’s alleged lack of comprehension was also unsupported by the recorded evidence and distinguishable from DPP v Falzarano.
6. The analysis was admissible. The case was remitted to the magistrates for rehearing by a different bench, to be expedited. Costs were ordered against the respondent, but were not to be enforced without leave of the court.

• Magistrates sitting at Macclesfield: dismissed the charge on 12 August 2002 after excluding the blood-alcohol analysis under section 78 of the Police and Criminal Evidence Act 1984.
• High Court (Administrative Court): allowed the prosecutor’s appeal and remitted the case for rehearing by a different bench.