Hundreds of motorists who have received speeding fines in Norfolk have had their cases halted after a conviction was overturned on a technical point.
Michael Cutting, from Bracon Ash, near Norwich, proved in court his speeding fine was accompanied by an illegal letter asking him to admit the offence.
He said the letter omitted a statement the police manager was writing with the authority of the chief constable.
Norwich Magistrates' Court agreed and invalidated the speeding fine.
Mr Cutting, who was caught speeding by a mobile camera on the A11 at Snetterton, had been sent a standard letter asking him to disclose who had been driving the vehicle.
Cost to taxpayer
He said he was unconvinced by the letter and thought it was a joke.
In the letter he was potentially being asked to incriminate himself and he claimed such letters should be sent only on the authority of the county's most senior officer.
When he appeared at court prosecution lawyers failed to present a case and said discussions were under way to assess the validity of letters sent out with speeding fines.
A spokeswoman for the Crown Prosecution Service said on Friday that cases would be adjourned while talks took place to clarify the situation.
She said discussions were being held with lawyers to assess the wider implications and the cost to the taxpayer.
Mr Cutting said he had used web sites to get advice on ways to present his case and challenge the speeding fine.