Investigators say the tech giants are generally helpful when tracking down the more serious and persistent law-breakers. However, many believe a lot of vicious online abuse does not hit the criminal threshold for charges to be brought. One said: “The level which it has to hit before it comes an offence is set too high. Because it doesn’t hit a threshold, the police are not allowed to start looking at identifying who that person is. “Facebook and Twitter would just say they’re not breaking the law and they are not breaching our conditions, so we can’t help you.”