One of five protesters arrested at the September World Bank summit was acquitted yesterday of disorderly conduct.
Moments after the acquittal, the prosecution sought to amend similar charges against two other defendants.
Tam Wai-pang, 25, was freed by Eastern magistrate Richard Donald after Lawrence Lok SC said his client had no case to answer.
The student had denied a charge of disorderly conduct after allegedly breaking through a police cordon in O'Brien Road, Wan Chai, on September 21.
The arresting officer said it was chaotic at the time of the arrest and agreed to withdraw his evidence after a video of the incident failed to show Mr Tam's conduct was disorderly.
Two other protesters jointly charged with Mr Tam - Tam Chun-yin, 25, and Wong Shui-ying, 39 - also deny disorderly conduct. Wong Shui-hung, 21, and Chan Siu-ping, 24, deny four charges of assaulting police officers.