There are a number of methods used by the police in the enforcement of speed limits: for example; radar, VASCAR, lasers, cameras and the police speedometer.
In December 2011 ACPO produced their “Guide for the Operational Use of Speed and Red Light Offence Detection Technology”. This followed the withdrawal of the previous Code of Practice in December 2008. The introduction to the new guide states its purpose is to allow operators of type approved equipment to achieve a consistent standard wherever it is used.
It must be stressed that this document is a guide, however in relation to laser speedmeters it recommends that sight alignment verification is carried out before and after each speed enforcement session. What this means is that the enforcement officer should ensure that the sighting scope on the device (infrared dot) is aligned with the laser beam at each enforcement site. This is to ensure that the vehicle and point on the vehicle the officer targets are the same as the laser beam is targeting.
In relation to distance and speed accuracy, the Guide states that for operator confidence the instrument may be periodically tested for range or speed accuracy on a target of known speed or distance. It refers the user to the manufacturer’s handbook for details of the check to be carried out. Because the accuracy of a known distance is required, such tests are not usually conducted at the enforcement site but are normally carried out at the police station before and after the enforcement session.
When using speed detection equipment, the officer should produce evidence as to the manner in which the equipment was used and, as such, any verification tests conducted should be noted contemporaneously and will form part of the evidence trail. These tests should concord with the manufacturer’s instructions, which should be available to the Court.
The laser speedmeter when used correctly is a very accurate instrument, however, poor operational practice can result in erroneous readings: lines of sight must be chosen carefully to ensure there are no other reflecting surfaces (e.g. road signs) between the operator and the target vehicle; the target vehicle must be travelling in a straight line at time of reading (e.g. not round a bend); and due to the complication of refraction the instruments should not be used through vehicle windscreens. We have seen all of these cause errors in evidence.
James Keenan, Mark Littler, David Winstanley and Dr Hayley Ash are experts at Keith Borer Consultants and specialise in the investigation of road traffic accidents, speed enforcement technology, vehicle examination and so on. Please contact our Durham office on 0191 332 4999 if you would like to discuss your case further.