Const. Babak Andalib-Goortani is charged with assault with a weapon over allegations that excessive force was used at the G20 summit in 2010, linked to injuries suffered by protester Adam Nobody.
The charge was laid by Ontario's police watchdog, the Special Investigations Unit. During his arrest, Nobody had his nose and cheekbone fractured.
The Crown and defence both asked for a postponement until Wednesday after a new video showing a different angle of Nobody's arrest was turned over by the SIU late last week. Both sides asked for more time to review the video, the fourth to be submitted as evidence in the case.
Andalib-Goortani was charged six months after the 2010 summit after members of the public came forward with video to help identify him.
A separate trial is set for next year for Andalib-Goortani, 30, on a second charge of assault with a weapon that was laid by Toronto police.
Andalib-Goortani is believed to be one of five officers who tackled Nobody, but could not be identified at the time because he had allegedly removed his nametag.
The trial is expected to take about two weeks.
Another officer not guilty
Last week, Const. Glenn Weddell, the other Toronto police officer who faced criminal charges, was found not guilty of assault.
A judge ruled there wasn't enough evidence to prove beyond a reasonable doubt that Weddell shoved and hit a protester.
Police came under intense criticism for their handling of the protests.
The vast majority of the more than 1,100 people detained in what Ontario Ombudsman Andre Marin called "the most massive compromise of civil liberties in Canadian history" were released without charge.