A Wiltshire policeman convicted of assaulting a woman in custody has been cleared on appeal.
Sgt Mark Andrews, of Wiltshire Police, was filmed dragging Pamela Somerville through Melksham police station in July 2008.
The officer was found guilty of causing her actual bodily harm and jailed for six months in September.
Sgt Andrews spent six days in prison, but was released on bail pending the appeal at Oxford Crown Court.
The appeal judge, Mr Justice Bean, said after the four-day hearing he was satisfied that Sgt Andrews did not intend to throw Ms Somerville into the cell and that injuries she suffered "were probably caused by her falling to the floor after letting go of the door frame".
She had been arrested for failing to take a breath test but was never prosecuted.
After Sgt Andrews won his appeal, Wiltshire Police announced that an independent force would hold an internal conduct hearing into the officer's behaviour in early December.
Sgt Andrews told the appeal hearing that Ms Somerville, 59, was the most unpredictable prisoner he had ever come across and that she had been abusive to both him and his colleagues.
The court was shown CCTV footage in which he is seen throwing her on to the cell floor. A minute later she staggers to her feet, with injuries to her face and eye.
Sgt Andrews told the court: "I don't think I did anything wrong.
"She had been holding on to the cell door frame when she suddenly let go.
"It was like pulling a cork out of a bottle."
Ms Somerville was arrested after she was found asleep in her car near her Colerne home and had been detained for failing to provide a sample for a breath test.
She denied any wrongdoing and the charges against her were later dropped due to insufficient evidence.
Sgt Andrews' barrister Jeremy Barton had put it to her at the appeal court that she had been so drunk on vodka the night the incident happened that she was an unreliable witness.
Mr Barton also suggested that she had refused to take a breath test because she knew how drunk she was.
Ms Somerville denied both of these claims.
Sgt Andrews was suspended on full pay following his conviction and had been expected to lose his job.
Following his conviction, Assistant Chief Constable Patrick Geenty said he was "a disgrace" to the force and added: "There is no place in Wiltshire Police for an officer like this."
Mr Geenty said at the time he fully supported the comments of the trial judge, Deputy District Judge Peter Greenfield, who said the officer had "presided over an atmosphere of bullying and intimidation upon Ms Somerville".
Following Sgt Andrews' conviction being quashed, Mr Geenty said due to the high-profile nature of the case the result of the conduct hearing into the officer's behaviour would be made public.
He said: "Sgt Andrews will remain suspended from duty until the conduct hearing and in accordance with national police regulations he will continue to receive full pay for as long as he remains a member of the force.
"Although this appeal hearing has concluded that no criminal offences had been committed we are determined to learn any lessons that emerge from this case and we welcome the fact that the Wiltshire Police Authority has commenced its own independent review of our custody practices."
In a statement a Wiltshire Police Authority (WPA) spokesman said: "I said at the time of the initial conviction that I thought this was an appalling but isolated incident.
"I now need to look carefully at the judgement as I looked carefully at the CCTV footage. It would not be appropriate for me to say more at this stage."
He said the disciplinary hearing will proceed as previously planned and an independent review into custody arrangements in Wiltshire was almost complete.