A civilian detention officer has been cleared of assaulting a prisoner at a police station after an appeal.
Judge Tony Briggs, sitting at Teesside Crown Court with two magistrates, cleared Michael Mount of assaulting unco-operative David Healer at Peterlee Police Station in March last year.
But his colleague Stephen Harvey, an experienced custody sergeant, failed in his bid to overturn two assault convictions.
The Durham Police employees appealed against their convictions at Teesside Magistrates' Court earlier this year.
Harvey, 50, from Chester-le-Street, twisted Mr Healer's arm when he would not answer questions while he was being booked in following his arrest for breach of bail and assaulting a police officer.
A video camera caught the incident and also Mr Healer's howls of pain.
After conviction, the Independent Police Complaints Commission described what happened as a form of torture.
Judge Briggs said Harvey was undoubtedly a man of good character with a long service record whose colleagues spoke in glowing terms about him.
But, at the end of a 10 hour shift and when he had been asked to work two more hours, he used the painful arm lock to make Mr Healer respond to questions, the judge said.
The sergeant had claimed he was using reasonable force.
Mr Mount, 61, from Thornley, was expected to assist the custody sergeant and follow his lead. He twice held Mr Healer by the wrist or arm.
"We are not satisfied that he acted unlawfully," the judge said of Mr Mount.
Harvey was ordered to pay £600 appeal costs. His original fine of £400, with £50 compensation to the victim still stands.
Mr Healer, who attended the hearing, is suing Durham Police.
Outside court, his solicitor Stephen Gowland said: "In the year this assault occurred, 23 people died in police custody in England and Wales.
"My client thought he was going to die in the police station and be part of those statistics."