A Canadian judge handed protesters of the G20 summit in Toronto a small victory today, restricting the use of a controversial sound cannon for crowd control, according to Reuters. Toronto police agreed to amend their guidelines for use of the cannon, keeping volumes below the maximum and not using the device from close distances. The portable loudspeakers are also known as sonic guns because the volume, specifically on the "alert" function that emits an ear-piercing beeping sound, can be turned up so high they can be used as weapons. "I have concluded that a very real likelihood exists that demonstrators may suffer damage to their hearing from the proposed use of the Alert function at certain distances and volumes," Ontario Superior Court Justice David Brown wrote in his ruling. The Canadian Civil Liberties Association and the Canadian Labour Congress had sought an injunction curbing police use of the cannon, and their lawyer, Paul Cavalluzzo, said Toronto police "went overboard." "What this application shows ... is that the police are accountable to the citizens of Toronto, that police are there to serve and protect us, not to endanger our safety," he said. Police said they hoped they would never have to use the device. "We'll use the alert if necessary in accordance with the guidance by the court," police Staff Superintendent Jeff McGuire said. "We would hope not to have to use it and quite frankly I'd be surprised if we do."