Two class-action lawsuits arising out of the chaotic Toronto G20 summit more than six years ago appear destined for trial after the country's highest court refused on Thursday to get involved.

Toronto's police authorities had wanted the Supreme Court of Canada to stop the legal actions in their tracks. The court, however, declined. It also ordered the police services to pay costs of the appeal.

Sherry Good, one of the two lead plaintiffs, said she was delighted the case could now move forward.

"We've been fighting for over six years now and we're committed to another six if it's necessary," Good, 58, said in an interview. "We want justice no matter how long it takes."

The class actions were spawned by the violence-marred weekend in June 2010 when police arrested or detained more than 1,000 people in what was later described as one of the worst violations of civil liberties in Canadian history. Many of the detainees were kept in appalling conditions at a makeshift detention centre in Toronto. Almost all were released without charge within 24 hours.

Good and co-plaintiff Tommy Taylor are seeking a court declaration that class members' charter rights were violated. They are also are looking for damages they say would be strong "instruments of behaviour modification." It's not clear when any trial might take place.

"Nothing is going to get in our way," Good said. "This is about freedom and democracy. The police need to know we're not going to stop until we make sure this never happens again."

After one false start and two bruising court battles, Ontario's top court in April ruled that the two separate but related civil actions -- one for people boxed in on the streets, the other for those sent to the detention centre -- should go ahead.

In turning to the Supreme Court, the police services board argued class actions were inappropriate. Instead, the board maintained any claims of wrongful arrest or detention should be treated individually. It also suggested the formulations of the class actions were unfair.

The board did not respond immediately to the Supreme Court decision on Thursday.

Good's lawyers said police now risk multiple lawsuits if they ever indiscriminately arrest entire crowds of demonstrators again.

"This case is about the right of everyday Canadians to publicly speak their minds without being arbitrarily rounded up and thrown in jail," lawyer Eric Gillespie said in a statement.

Good was among scores of people police "kettled" in torrential rain at a downtown intersection, while Taylor was sent to the makeshift east-end detention centre.

Both she and Taylor want damages for false arrest or imprisonment, and violations of their constitutional rights. They maintain a senior officer gave orders for the indiscriminate roundup of anyone present at various downtown locations -- including peaceful protesters, bystanders and journalists. Police also conducted "humiliating" strip searches and "needlessly beat people," they say.

Last year, a tribunal convicted Toronto police Supt. Mark Fenton of misconduct for ordering the mass arrests. He was given a formal reprimand and docked 30 days' vacation. Fenton is appealing.

In an even earlier ruling allowing the class actions, Divisional Court said the mass arrests could be seen as "one of the hallmarks of a police state."