A riot squad officer who hit a G20 protester twice with a metal baton was cleared of assault today.
Metropolitan Police Sergeant Delroy Smellie, 47, clashed with animal rights activist Nicola Fisher outside the Bank of England last April.
The officer, a member of the controversial territorial support group, went on trial accused of assault by beating last week.
He was cleared today at City of Westminster Magistrates' Court.
But he could still face misconduct proceedings over the incident.
Smellie, who was standing in the dock for the verdict, smiled widely and gave two thumbs up to his supporters as he was cleared.
District Judge Daphne Wickham said there was no evidence that his use of the baton was not approved, correct or measured.
She said the officer had a "mere seven seconds" to act and other witness also feared for his safety.
She said: "It was for the prosecution to prove this defendant was not acting in lawful self-defence.
"I have found the prosecution has failed in this respect and the defendant has raised the issue of lawful self-defence and as such is entitled to be acquitted."
Ms Fisher, 36, ran in front of Smellie hurling abuse during a vigil to mark the death of Ian Tomlinson the previous evening.
District Judge Wickham, who heard the case without a jury, watched video footage of the incident and looked at dozens of photographs.
Nicholas Paul, of the Crown Prosecution Service, said Smellie lost his self-control because of Ms Fisher's irritating, aggressive and confrontational actions.
He said the officer was justified when he shouted at her, pushed her back and struck her with the back of his hand, knocking off her sunglasses.
But Mr Paul said the officer went too far when he struck Ms Fisher across the thigh with the extendable metal weapon, known as an asp.
The clash attracted attention worldwide when amateur video footage of it was posted on the YouTube website.
Ms Fisher, of Brighton, suffered two bruises to her leg and enlisted Max Clifford to sell her story to a national newspaper for around £26,000.
She failed to attend the trial claiming she was suffering depression and did not want to be in the public spotlight again.
In his defence, Smellie said he feared for his safety when he was left isolated behind a line of his colleagues who were facing the other way.
The highly-trained and experienced officer, who has been suspended from duty for almost a year, said his actions were reasonable and proportionate.
Smellie said he mistook a carton of orange juice and a camera in Ms Fisher's hands as weapons when she approached from his "blind-side".
He had been on duty for about 28 hours with only a three-hour break when his unit received an urgent call to join colleagues in the City on April 2.
A line of City of London Police officers had complained of being hit by missiles as a large group of people gathered, some of whom were hooded and carrying flags.
Smellie has served at some of the most volatile protests of recent years, including those marking a visit by US president George W Bush.
Colleagues described him as an exceptional and totally dedicated officer who served as an example to others.
Ms Fisher's media adviser Max Clifford said she would be "very disappointed" by the outcome and that she was expecting the officer to be cleared.
Mr Clifford said: "All I can say is that she would see this as a total miscarriage of justice and that it doesn't surprise her.
"He is a police officer, she's a protester so she's obviously very disappointed.
"She sees it as a total miscarriage of justice. She was convinced that she wouldn't get justice."
Smellie left court without commenting flanked by his legal team, several colleagues and Police Federation representatives.
Asked inside the building if he was going to say anything, he replied: "I don't think so, I have got a reputation to protect."
Ms Wickham spent about 20 minutes explaining the reasons behind her decision.
She said Ms Fisher was moving around quickly, shouting and calling at Smellie "seeking confrontation" and could be seen "playing to the cameras".
Ms Wickham said there was no definitive record of events, despite the amateur video footage and large number of photographs presented to the court.
Describing the demonstration she said: "It was probably an anti-police gathering with some chanting and flag waving, but it did not present as public disorder."
The judge added that a convoy of police "tank vehicles" inflamed tensions when it drove down Threadneedle Street and Ms Fisher acted after a man attempted to leave the police cordon.
She said: "I am satisfied this empowered Ms Fisher to get involved in a strongly exhibitionist and aggressive way."
Ms Wickham described how Ms Fisher was part of a crowd that surged towards Smellie who could not see officers to his right who could have helped him.
She said: "I am satisfied he honestly believed it was necessary to use force to defend himself."
Ms Wickham said Smellie could not use other options, such as enlisting help from the police cordon, spraying CS gas, hitting Ms Fisher with his elbow or arresting her.
She said the officer deliberately bent his knees to ensure his strikes hit Ms Fisher on the thigh to inflict a "transient flesh wound".
The court heard Smellie had a "punishing schedule" with just three hours break during 28 hours of duty and that he started work at 5am that day.
Ms Fisher said she was "disappointed" by the verdict.
She added: "I'm just glad it's all over. It has been a nightmare. I stand by what I said (against the officer)."
She declined to comment further.
Deborah Glass, of the Independent Police Complaints Commission, said Smellie could still face a police punishment.
She said: "People were understandably concerned when footage of this incident was played out on the internet and television and it is right that the actions of the officer were independently investigated and put before a court.
"The evidence shows that we carried out a balanced investigation and the CPS presented a balanced case.
"Following today's decision, we will submit our report to the Met for their consideration in relation to any appropriate misconduct sanctions."