Police are to be given new guidelines on using mobile speed cameras because of concerns that they are breaking the law by trapping motorists at too great a distance.

Laser cameras, which can either be handheld or mounted in vans, are certified by the Home Office for use at a range of up to 1,000 metres (3,281ft).
But the law states that a camera operator must be able to form a "prior opinion" that a vehicle is breaking the limit before using the camera to record its speed. The law dates from the days before radar speed guns when all that was needed to convict a driver of speeding was the opinion of two officers.