A "secret" law that gave sweeping powers to police during the G20 summit this summer will be reviewed by a former Ontario chief justice.

Roy McMurtry is set to review the Public Works Protection Act, a Second World War bill originally passed in 1939 and intended to protect government buildings in the case of home front attacks during the war.

The act was quietly updated, for the first time, last June, ahead of the G20.

The law gave police the power to stop, question and arrest anyone within five metres of the G20 security fences that snaked through downtown Toronto streets.

The law applied to only those within the security fence but was misrepresented, making it seem the law also applied outside the secured zone.

The interpretation of the law fuelled a series of protests following the summit to demand an inquiry into police tactics against protesters. Premier Dalton McGuinty and Prime Minister Stephen Harper have rejected the possibility of a public inquiry.

McGuinty has admitted the province should have told the public about the law, saying he wrongly thought the police would send out an alert.

More than 1,100 people were arrested during the summit, most of who were released without being charged. Many more have since had their charges dropped.

"We need to make sure our laws reflect the security concerns and values of our society today," Community Safety and Corrections Minister Jim Bradley told the Toronto Star on Tuesday.

"That includes maintaining both public order and freedom of expression."

McMurtry was attorney general between 1975 and 1985 under then-premier Bill Davis. He will make his recommendations to the government by next spring.