The ruling by the Ontario Court of Appeal overturns a lower court finding that Sgt. Mark Charlebois had only touched Paul Figueiras at the June 2010 event in downtown Toronto.
"Even if Sgt. Charlebois was authorized to stop Mr. Figueiras and demand that he submit to a search, I do not accept that the grabbing and pushing that occurred here were 'necessary' to achieve this purpose," the Appeal Court found.
"Sgt. Charlebois committed the tort of battery."
The weekend G20 summit was marred by vandalism and the largest mass detention and violation of civil rights in Canadian peacetime history.
The particular incident occurred when a group of York Regional police officers brought in for the summit stopped Figueiras and his friends — who wanted to demonstrate in favour of animal rights — and told them to submit to a search if they wished to carry on walking down the street.
Figueiras refused, arguing the request violated his rights.
Charlebois's response — caught on widely viewed video — was to grab Figueiras, push him away and tell him to "get moving."
"There's no civil rights here in this area," Charlebois told him. "This ain’t Canada right now."
The protester turned to the courts, seeking only a declaration that the officers had violated his constitutional rights and that Charlebois had committed battery by grabbing and pushing him.
In the lower court ruling, Ontario Superior Court Justice Frederick Myers found police had acted lawfully and that any force Charlebois used was minimal and justified.
The Appeal Court disagreed on both counts.
"Rule of law is a fundamental principle of the Canadian constitution," the court said.
"The actions taken by Sgt. Charlebois and his team were not reasonably necessary and had little, if any, impact in reducing threats to public safety, imminent or otherwise."
The officers, the court found, were not simply controlling access to an area as might happen at an airport or courthouse where they have specific authority to screen everyone. Instead they were targeting some people and forcing them to submit to a search — without any authority to do so.
"The intention motivating the police conduct was therefore to stop everyone who appeared to be exercising their freedom of expression, and to impose an onerous condition upon them," the court ruled.
"The officers' remarks further undermine the reasonableness of their conduct, and aggravate the harm to Mr. Figueiras’s liberty."
Police, the court concluded, violated Figueiras's constitutional right to freedom of expression, peaceful assembly, and liberty.
It ordered police to pay him $10,000 in legal costs.