DPP v Walsall Magistrates' Court & Anor

A section 8 disclosure application concerning a type-approved breath-testing device requires a proper evidential basis. The evidence must address both how the device could produce a materially false positive while appearing to operate correctly, and how the requested material could demonstrate that possibility. Generalised or speculative assertions are insufficient. An expired calibration certificate does not, without supporting evidence, justify wider disclosure. Evidence that a defendant consumed too little alcohol may support a challenge to the result, but historical device data must still be shown to be capable of assisting the defence. The statutory limit remains decisive; a prosecution policy margin above that limit does not create a separate legal threshold. Applications made late and likely to disrupt a fixed trial may also be refused under the criminal case-management rules.

The DPP brought two joined judicial review applications concerning prosecutions under section 5(1) of the Road Traffic Act 1988. In each prosecution, an approved Lion Intoxilyser 6000UK recorded a breath-alcohol reading above the statutory limit. Following defence statements and expert material, the District Judges ordered disclosure under section 8 of the Criminal Procedure and Investigations Act 1996, including device logs, historical test data and calibration records.

The DPP challenged whether the requested material might reasonably be considered capable of undermining the prosecution case or assisting the defence. In the second case, the DPP also relied on delay in pursuing the application. The central issue was whether the evidential and procedural requirements for section 8 disclosure had been met.

1. The applications were allowed. Permission was granted, both disclosure orders were quashed, and the proceedings were not remitted.
2. Under sections 7A and 8 of the Criminal Procedure and Investigations Act 1996, a defendant must show reasonable cause to believe that undisclosed prosecution material might reasonably be considered capable of undermining the prosecution case or assisting the defence. In cases involving an approved breath-testing device, the application requires a proper evidential basis.
3. Following the guidance in R (DPP) v Manchester and Salford Magistrates’ Court [2017] EWHC 1708 (Admin), the supporting evidence must address two matters: how the device could produce a substantially false positive despite its printout indicating proper operation, and how the requested material could assist in demonstrating that mechanism. The general assertion that a device may be unreliable is insufficient.
4. In Mr Bhusal’s case, the defence statement contained unsupported assertions. The expiry of the calibration-gas certificate justified an adjournment to investigate its significance, but did not justify wider disclosure without evidence establishing relevance.
5. In Mr Thaiss’ case, the expert evidence was generalised and unexplained. Even accepting a possible reduction of the recorded reading from 45 to 39 microgrammes per 100 millilitres, the result remained above the statutory limit of 35. The higher prosecution limit was irrelevant to the section 5 offence. The proposed abuse-of-process argument was therefore fanciful.
6. The delay in pursuing Mr Thaiss’ application, contrary to the case-management duties in the Magistrates’ Courts Rules 1981 and Criminal Procedure Rules, supplied a further reason for refusal. The court nevertheless rested its decision on the substantive evidential deficiency.
7. The court further observed that general challenges to the reliability of an approved device should be directed to the Secretary of State. Expert reports used to support disclosure must comply with the requirements concerning data, methodology, contrary opinions, uncertainty and reliability.

• High Court (Administrative Court): the DPP’s rolled-up judicial review applications were granted; the District Judges’ disclosure orders were quashed.