A significant proportion of speeding tickets are generated by mobile police lasers; the favourite seeming to be the notorious LTI 20-20. You’ll know these devices as they’re normally poking at you from a police van on a dual carriageway; motorway bridge or on the side of the road. The vans are usually easy to spot – if you’re keeping your eye on the road (!) – but sometimes the devices are operated by officers on motorcycles and these can be difficult to spot.
In that situation, the enforcement officer parks, usually at a pre-determined position, unpacks the equipment and begins his work.
These devices are normally operated by police enforcement officers (not police officers) and that is where the problems can begin for the prosecution. Some of these traffic enforcement officers are very good and have a sound understanding of what they are about; others sometimes, under cross-examination, demonstrate a less impressive understanding of the equipment they are using and the tests they should carry out (by way of alignment and calibration) on the equipment before setting out to catch you; the allegedly speeding motorist!
If you receive a speeding ticket, notice of prosecution, etc then you may receive with it a couple of photographs apparently showing you travelling at an alleged speed. Remember this, the photograph merely records the alleged speed. It is the laser device and the computer hardware within it which provides the evidence supporting the prior opinion of the officer concerning your speed. For the prosecution to succeed they must demonstrate that the equipment was properly calibrated and checked before and after they allegedly caught you: this is where the prosecution frequently fall down!