Dhaliwal, R (on the application of) v Director of Public Prosecutions Rev 1

In a prosecution for driving with excess alcohol, the prosecution must prove that the analysis was reliable, but it need not prove every laboratory step unless the defence fairly raises a relevant issue. The evidence required depends on the nature of the challenge. An analyst may give evidence of a belief, based on laboratory records and established procedures, that a check was performed. That evidence is distinct from hearsay evidence offered to prove as a fact that the check occurred. Where the defence has not challenged the presence or quantity of preservative, the prosecution need not prove those matters as separate ingredients of the offence. The court must assess whether the admissible evidence leaves it sure that the analysis was reliable.

The claimant appealed by way of case stated from a decision of the Wolverhampton Magistrates’ Court. He had been convicted of driving with excess alcohol. The prosecution relied on a forensic scientist’s evidence and certificate showing a reading above the statutory limit.

During cross-examination, the analyst referred to a laboratory record indicating that an assistant had checked for fluoride preservative. The central issue was whether the magistrates had unlawfully admitted hearsay evidence that the sample contained preservative and was reliable.

1. Appeal dismissed. The magistrates were entitled to conclude that the prosecution had proved the offence and that the analysis was reliable.
2. The prosecution’s essential evidence was the analyst’s reliable result. It was not required in every case to detail every step of the scientific procedure. The relevant question was whether the analyst was qualified and whether the recognised procedures necessary for a proper analysis had been followed.
3. The defence could raise any issue concerning the reliability of the analysis, by cross-examination or evidence. The evidence required to answer the issue depended on its true nature. Proper notice and disclosure were desirable to prevent trial by ambush.
4. The analyst could not give admissible hearsay evidence to prove, as a fact, that an assistant had checked for preservative or that a particular quantity had been added. She could, however, give admissible evidence that she believed the check had been carried out, where that belief was based on laboratory records and normal procedures.
5. The defence had not fairly raised an issue that the sample lacked preservative or contained an incorrect quantity. Its questioning concerned whether a check had been made. Accordingly, the prosecution did not have to prove the presence or quantity of preservative as an independent matter. The analyst’s evidence provided reasonable grounds for concluding that proper procedures had been followed and that the result was reliable.

1. Wolverhampton Magistrates’ Court: convicted the claimant of driving with excess alcohol.
2. High Court (Administrative Court): permission having been granted to state a case, dismissed the appeal by way of case stated.