A teenager has successfully defended himself against a speeding ticket by convincing the court that his GPS was more accurate than a police radar gun.

Shaun Malone, 18, was issued with a ticket after a police radar gun tracked him at 62mph in a 45mph zone.

However, he appealed against the ticket because his GPS, which was installed by his parents to monitor his driving, apparently showed that he was driving within the speed limit.

A court expert said originally that GPS was not accurate enough to give a precise reading. But after examining the particular system, installed by Rocky Mountain Tracking, he decided that it would be suitable.

"This case has caught the attention of the nation, and it will set a precedent on how police departments use speed traps in the face of an increased GPS presence," said Brad Borst, president of Rocky Mountain Tracking and a former police officer.

"The accuracy and reliability of GPS has helped bring this important issue into the limelight."

The device measures real-time speed every 30 seconds and can be configured to send an email message to the owners if the car reaches speeds of 70mph or over.