A police officer has been cleared of lying to avoid a speeding ticket after the judge ruled that the jury could not find him guilty.
Sergeant Alun Williams denied making up the story
Sergeant Alun Williams was accused of submitting a false exemption form for doing 102mph on the M4.
But Judge Phillip Richards said the "suspicion" that he had lied was not a good enough basis on which to convict him.
Mr Williams had denied perverting the course of justice.
During the hearing at Newport Crown Court the sergeant from Tonypandy, Rhondda, claimed he was following a suspected stolen car between Miskin and Pencoed on the M4 in May last year.
But the jury was told how he did not contact the control room or tell four other officers in the car what he was doing until he was caught by a speed camera going over the limit.
During the trial the prosecution alleged that he had made up a story.
He submitted the exemption forms between June and July 2004.
He told police he was chasing a white Volvo sports car but the jury was told that no car of that sort was on the motorway CCTV cameras at the time.
The court heard from Sergeant Alun Ifor Williams - also of South Wales Police - who said he had "gained an impression" that Sgt Williams had "engineered" his exemption claim.
Three other officers were in the car at the time, on their way back to police headquarters in Bridgend, but told the court they knew nothing about the chase.
Judge Richards told the jury on Friday that Mr Williams had given him the impression that an exemption had been submitted to avoid conviction.
"I don't think he used the expression 'false'," he said.
"The impression I got was that the exemption was engineered. It came across that it wasn't a big issue."
But directing the jury to find him not guilty, he said this "suspicion" was not a basis for a conviction.
He said: "One is bound to have suspicion, but suspicion is not enough to convict a person in this country.
"It is necessary that a jury can be sure of guilt," he added.
Speaking after the verdict Howard Casey, Deputy Secretary of South Wales Police Federation, said Sgt Williams had been "vindicated" but was awaiting any disciplinary matters that may arise.
"It would be inappropriate for us to make any comment, but we are totally happy that this officer has been vindicated," he said.
"He has served us in an exemplary fashion and will continue to do so."
An investigation was started after Sergeant Williams allegedly confessed making up the story to a colleague in the police canteen.