A bill that bans the wearing of masks during a riot or unlawful assembly and carries a maximum 10-year prison sentence ... became law today. The bill is meant to give police an added tool to prevent lawful protests from becoming violent riots, and that it will help police identify people who engage in vandalism or other illegal acts. The bill originally proposed a penalty of up to five years, but the House of Commons justice committee amended it and doubled the penalty to up to 10 years in prison for committing the offence. The bill didn't have unanimous support, and was opposed by some who are concerned about its effect on freedom of expression and privacy. Civil liberties advocates argued the measures could create a chilling effect on free speech and that peaceful protesters can unintentionally find themselves involved in an unlawful assembly. They also noted that there are legitimate reasons for wearing masks at protests; some may be worried about reprisals at work, for example, if sighted at a political protest. Any law that infringes upon civil liberties needs to be held to a test of absolute necessity, and I don't think that test has been met in this instance," said Michael Byers, a political scientist at the University of British Columbia.