New generations of GPS systems automatically and accurately track your speed - as one ticketed teenager armed with a navigation system and an ex-Sherrif father is arguing in court:

"According to [ex-Sherrif] Rude, all recorded plots on Malone's route show him to be driving under the speed limit. At the same time, Rude says, GPS-systems are clearly more reliable than radar systems, which, while good, are "not an infallible tool" and are subject to human error.

"A Sonoma County traffic commissioner has to decide whether the GPS system can be accepted as a basis to challenge the ticket, but ex-sheriff Rude is prepared to push his case in court in the event of an unhappy outcome."

More and more of these cases are coming up - so keep an eye on your GPS - it may get you out of your next ticket!

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