A scientist escaped a charge of speeding at 42mph, after claiming a device he invented showed him travelling 12mph slower.
Dr Tann claims his system is more accurate than mobile cameras
Sunderland University lecturer Phillip Tann, 45, was told mobile speed officers recorded him speeding in a 30mph zone in the city last November.
But Dr Tann, from South Shields, had data from a satellite tracking device, showing him travelling at 29.18mph.
The Crown Prosecution Service confirmed proceedings against Dr Tann had ceased.
Dr Tann was told he had committed the offence on Sunderland's Kier Hardie Way on 27 November 2006.
He was faced with a fine and penalty points, but contested the case and elected for trial at Sunderland Magistrates' Court.
Dr Tann's invention is built into a mobile phone and records its location and speed on a computer database.
The design has already received government funding, with a £60,000 NStar proof of concept award.
His company, Autopoietic Systems, plans to market a consumer version of the technology later this year.
The technology lecturer believes his case could open the floodgates for other motorists accused of speeding.
He also called for better training for police officers who have to use mobile speed detection equipment.
Dr Tann said: "The mobile cameras used are not 100% accurate.
"My system can track a GPS phone within half-a-metre of where it is, whereas devices currently on the market can, at best, only track a phone within five metres."
A spokesman for the Crown Prosecution Service (CPS) said: "The officer who operated the camera has since retired.
"Without his verbal evidence, we could not prove the case to the required standard."