The G20 Summit saw the largest mass arrests in Canadian history, with over 1000 people arrested between June 18 and June 28—roughly eight times the number of arrests at the last G20 summit in London England, and twice the number of people detained during Canada's 1970 FLQ October Crisis, when the War Measures Act was triggered.

"Canadians are entitled to policing that does not undermine constitutional values," stated the Canadian Civil Liberties Association (CCLA). More than 50 CCLA human rights monitors were on the streets during the Summit, adding, "In an effort to locate and disable 100-150 vandals, the police disregarded the constitutional rights of thousands."

The Ontario McGuinty government decision to pass a temporary Regulation under the Public Works Protection Act has come under fire. The Regulation was quietly passed June 2, 2010 but not published in the Gazette until after it expired.

The police investigating their own actions has not satisfied concerns. All four federal opposition parties in Canada's House of Commons have now backed to the call for an independent inquiry, making a federal inquiry likely.