Haggis v Director of Public Prosecutions

Evidence from a trained operator that an approved breath-testing device was working properly may support a conviction even though the operator cannot state the machine’s precise calibration limits. The operator’s evidence is a matter for assessment as a whole, and a gap in knowledge does not automatically deprive the witness of trained-operator status. An approved device may be presumed to perform its self-calibration function unless circumstances indicate that it may not have done so. The prosecution need not prove the self-testing mechanism on every occasion. The court must consider whether the evidence, including the printout and surrounding circumstances, raises a reasonable doubt about the machine’s operation.

The claimant appealed by case stated from the decision of Deputy District Judge Singleton at Liverpool Magistrates’ Court, who convicted him of driving with excess alcohol. The prosecution relied on a Camic Datamaster breath analysis showing a lower reading of 43 microgrammes of alcohol in 100 millilitres of breath. The operator was trained and said that the machine was self-calibrating and working properly, but she did not know the correct calibration limits. The claimant challenged the sufficiency and reliability of the evidence. The case stated two questions concerning the operator’s status and whether the conviction was safe on the evidence.

1. The appeal was dismissed. The court answered yes to the first question and no to the second.
2. A trained operator’s inability to state the precise calibration limits does not, by itself, prevent the court from accepting that witness as a trained operator. The issue is factual. The court must assess the quality of the evidence and the extent to which the gap in knowledge undermines the operator’s evidence that the machine was functioning properly. The judge was entitled to conclude that the operator remained properly described as trained.
3. Denneny v Harding (1986) RTR 350 concerned an untrained officer who had merely observed a display reading. The observations of Watkins LJ had to be read against those facts and did not impose a statutory-instrument-like requirement in every case. The present case was materially different.
4. The self-testing characteristic of an approved device was recognised in Cracknell v Willis (1988) AC 450. The prosecution did not have to prove on every occasion that the machine had carried out its self-calibration. It could be taken that the device had tested itself unless something indicated that it might not have done so in the particular circumstances.
5. Mayon v DPP (1989) RTR 281 was distinguishable because there was evidence of a possible machine failure, including an aborted result and accidental unplugging. Here there was no comparable evidence. The operator’s evidence that the machine was working properly was unchallenged in any material respect, and the reading was consistent with the other evidence. The judge was therefore entitled to conclude that no evidence raised a doubt about the machine’s operation.
6. The court also distinguished Lonergan v DPP (2003) RTR 188, which involved materially different timing and evidential circumstances. Lord Justice Brooke added practice guidance concerning timely skeleton arguments and bundles of authorities, with possible costs consequences for non-compliance.

• High Court (Administrative Court): Deputy District Judge Singleton convicted the claimant at Liverpool Magistrates’ Court. The High Court dismissed the appeal by case stated and answered the two questions posed as yes and no respectively.