It's almost a common sense application of the law. You require identity. The courts in Canada require a pretty strict interpretation of identity to successfully prosecute. I know the efforts and the time the Vancouver police have put into identifying the rioters so far is staggering. The cost is staggering.
This kind of legislation would allow us ahead of time to send a very strong deterrent message to those individuals who are contemplating wearing a mask that their conduct will be observed and preventive arrests could be made.
In the midst of an unlawful assembly, it's extremely difficult to commit resources to actually enter a riotous crowd to take people into custody. You simply don't have enough officers, and that goes against the basic tactics of crowd dispersal we've all been trained in. The officers we send to attend these kinds of riots don't ask for much from Parliament. They only ask for the tools and the legislation to help them do their jobs as well as possible.
There's no group more committed to human rights and to lawful protest than the police. I have countless letters from organized groups in Vancouver thanking us, after protests, for the way the police engaged with the crowd to make it lawful. If they were here, many would condemn bad behaviour also, because it takes away from the legitimate message that comes with lawful assemblies.