Speedometers over state the speed by up to 10%, so are possibly less accurate than GPS devices. But anyhow regardless of that, given the story about that inventor who PROVED that he was going CONSIDERABLY slower than he was accused of, there appears to be a chance that he was under the speed limit (either according to his speedometer or not).
If these types of camera's are not completely accurate then they should be banned. PERIOD. Everyone knows these are just money making scams by the police, so they probably don't really care about the accuracy unless the public begin to realise that it is a big CON or get ‘outed’ in public (like that inventor did).
Why haven't all forces reviewed their policy on using these camera's? Why... because their inaccuracy is making them money. When you get the ticket, it tells you that if you contest it they might decide to make the punishment worse. Surely that's blackmail?! But it works, and most people give in for fear of greater punishment.
Camera Safety Partnership - pah! Jobsworths the lot of them. They need there to be an issue so they can all have jobs. No-one is independent. Speed is a contributing factor to the amount of impact in an accident, but in most cases is NOT the CAUSE. If speed = crash, then why don't most plane's always crash when they take off. The most common cause of an accident is bad driving (or driving error). To solve this, get more Police actually out there driving around, picking up people with bald tires, no lights, or driving like an idiot.
This comes from a frustrated driver who is fed up with being taken as a mug by a bunch of money grabbing morons. I know very few people who haven't had points on their license, and those that haven't I don't know many who haven't come close. And fact, I know of no-one who hasn't sped at at least one point in their life - shock, horror... anyone who says they haven't is either a complete liar or is one of those drivers who should be pulled over for going 35 in 60 zones (clearly not recognising the national speed limit sign).