Speeding Offences & Accuracy of Speed Detection Devices

An interesting point arose in a recent speeding trial. The accused was charged with driving at 43 mph in a 30mph zone. The Crown case consisted of two Police officers, both of whom were experienced road traffic officers, trained in the operation and calibration of the standard issue speed detection device, the Unipar SL700.

Both officers provided statements describing the various checks carried out at the beginning and end of their shift, with the alleged offence sandwiched in between these book ends. There was no issue with the calibration check operated by the officers; it was very thorough and comprehensive. The officers signed a routine evidence certificate under section 280(1) of the Criminal Procedure (Scotland) Act 1995 to say that the device was accurate upon their check.

No objection was taken to the officers' contention. However, the issue was that the manufacturer's calibration disclosed by the Procurator Fiscal was 3 months out of date. The manufacturer's certificate is effectively an annual MOT which validates the individual speed detection device. In evidence, the officer accepted that the Police calibration is limited to scope alignment, visual display integrity and fixed distance. In contrast, the manufacturer's calibration is carried out by a technician and extends to internal checks and installation and replacement of parts where required. The officers accepted that they have no training in such matters and that on a number of levels, the manufacturer's check goes beyond their examination at the start and end of their shift.

Critically, the manufacturer's certificate is signed off on the basis that the device being examined is of a type that is home office approved. In the absence of a valid certificate, there is an argument that there is a doubt as to the accuracy of the device and also, that the device does not enjoy approved status. It was accepted that there are two essential pillars to accuracy; the officer's check and the manufacturer's warranty. If one or both is missing, the device can not be said to be accurate or of a type that is approved by the Home Office. Indeed, clause 10 of the Schedule to the Home Office Agreement for Light Beam Speed Measuring Devices requires the company to issue an annual certificate of validation. Every speed testing device must undergo this process to stay on the approved list and the Police check of accuracy, however thorough and comprehensive, is rendered void without the valid calibration certificate. The speed device itself (not the check by the Police witness) can not be relied upon in the absence of this certification.