Sgt Delroy Smellie confronted Nicola Fisher at the G20 protests
A G20 protester allegedly assaulted by a police officer was acting like a "lunatic", a court has been told.
Witnesses told Westminster Magistrates' Court that Nicola Fisher was aggressive during the demonstration in central London last April.
Metropolitan Police sergeant Delroy Smellie, 47, denied a charge of common assault against the 36-year-old animal rights activist from Brighton.
Prosecutors say he committed a crime by striking her twice with a metal baton.
The clash was caught by several cameramen and photographers, and the video of it was posted on YouTube.
Two office workers, giving evidence for the prosecution, told the court how they watched a confrontation between her and Sgt Smellie.
Mark Ellul said his eyes were drawn to Ms Fisher as she was "hyperactive" and behaving "erratically" in the moments before the clash.
His colleague Tracey McDonnell said Ms Fisher was "playing up to the cameras" and throwing orange juice at the officer.
She said: "There were a lot of people there but we were drawn to her as she was bouncing around and the most aggressive person there at the time."
Mr Ellul and Miss McDonnell said they contacted the Independent Police Complaints Commission (IPCC) after watching media coverage of the incident.
Both said they felt the coverage gave an unfair and inaccurate portrayal of the officer's actions.
Mr Ellul added he felt Sgt Smellie was vulnerable because he was caught behind a line of officers who were looking in the other direction.
Miss McDonnell said the group of protesters had been "antagonised" by the arrival of a large convoy of specialist police vans carrying public order officers.
The court heard Miss McDonnell described Ms Fisher as behaving like a "lunatic" and being "out of control" in a statement she gave to the IPCC.
The case continues.