The rules police must follow when nicking you for speeding are complex and thorough. Our guide to them will equip you to make the most of your rights should that summons come.
This article was put together by Steve Farrell for Motorcycle News with the aid of Chris Taylor, of Cephos Electronic Circuits Limited. He has worked closely with manufacturers of speed detection devices used by the police.

TO GET AN ACCURATE SPEED CHECK, YOUR BIKE MUST BE THE ONLY VEHICLE IN THE FIELD OF VIEW:
The Association of Chief Police Officers (ACPO) has its own manual on speeding procedures. It states "Radar speed meters are designed to measure the speed of one vehicle at a time. Should there be more than one vehicle present in the radar field of view, it is possible for the device to detect two different signals and alternately display different speeds, in which case the check must be aborted."
That means that if there’s another vehicle around, the speed on the radar may be the speed of that vehicle and not your bike, and the evidence should be scrapped even if the vehicle was a long way behind you.
"It is quite possible for the signal from a large vehicle some distance behind a smaller vehicle to override the signal from the nearer vehicle," says the manual.
The guidelines warn that "An operator must not measure and make detections for prosecution when more than one vehicle is within the radar detection range."
The same rules apply to unmanned speed cameras, including GATSOS. With reference to the photographic evidence these devices rely on, the guide says: "Where there is a suggestion in the negative that two or more vehicles are or may be in the measurement field, the reading should be disregarded."

THE SPEED CHECK MUST BE DONE IN LINE WITH YOUR BIKE’S PATH:
This applies to both handheld radars and lasers. It means that the speed check must be done from a position directly in front of your bike, on a straight stretch of road. If it’s not, the reading will be inaccurate and should be scrapped.

THERE MUST BE NO LARGE ROAD SIGNS, HOARDINGS, PILLAR BOXES, BUS STOPS OR OTHER LARGE STATIONARY OBJECTS IN THE AREA:
According to the manual, objects such as these can reflect and scatter the signal from a handheld radar, making accurate speed measurement impossible. "It is therefore an important requirement to check a site before starting measurements," it says. "The operator should always select a site with a clear view of the oncoming traffic which is free of any large objects such as bus shelters, large road signs and metal fences or crash barriers which are close to the radar. To avoid multiple reflections, the radar must not be operated under or through bridges or railway arches," it continues.
It goes on to say: "Police radio transmitters, whether handheld or car mounted, must not be used at the moment a vehicle speed is being measured." The site must also be away from high voltage overhead lines, transmitting masts or towers, airports or harbours, or places where high power radio transmitters may be expected.

HANDHELD RADARS MUST BE AIMED AT YOUR BIKE FOR A MINIMUM OF THREE SECONDS FOR A VALID CHECK, WITHIN A DISTANCE OF 200 METRES:
Once a reading has appeared on the display, the radar device should be held steady, pointing along the road for a duration of not less than three seconds. During this period a steady reading must be obtained which equates to the observations of the operator.

OFFICERS USING HANDHELD DEVICES SHOULD BE CLEARLY VISIBLE AND SHOULD STAND AT THE SIDE OF THE ROAD, NOT ON THE CENTRAL RESERVATION:
This applies to both laser and radar equipment. "Handheld radar speedometers should only be operated by an officer on foot," says the manual, before later stating that "operators of devices should normally do so from positions where they will be clearly visible to the public.