The request for information on the usage of the Pro Laser III Handheld Speed Detection Device was sent to the Home Office Scientific Development Branch (HOSDB) on 19 July 2010. We released the following information on 16 August 2010.
There are no instructions regarding the status of the vehicles electrical system/ignition system when using a Pro Laser III device.
The Pro Laser III requires at least 0.3 sec of signal to generate a reading. This corresponds to a vehicle travelling at 55 mph to travel 8 yards before a measurement can be displayed.
The police do not normally target every passing vehicle. However there is no reason in law that disallows such use.
The device only displays a speed reading when it has received a sequence of signals consistent with one vehicle travelling at that speed.
The speed displayed is the speed when the officer released the trigger of the Pro Laser III device.
Any part of the vehicle can be used to get a measurement. However, a reading will only be generated when an adequate signal to generate a reliable measurement has been received.