Unfortunately this is already illegal in some other western countries for quite some time. In Germany for example since 1985 (one year late though). It's often used as legitimation when the police is using violence against otherwise peaceful protests.

In the aftermath of the G20 summit in Hamburg there were some advancements to even tighten the law while at the same time the police was using illegal face recognition software.

Yet to be tried in court, I think. I suspect, that unless someone is using a facial covering to hide their face while breaking the law, it would probably be found against the charter. One does not need to identify law abiding citizens and protesting is very protected expression.

Not a lawyer though, so I speak with little authority on the topic.

In the solidarity protests for HK in Vancouver almost everybody wears them for obvious reason. Would be interesting if Canadian police require to remove them...

In Austria it's illegal to wear a face mask if it's not cold enough or for special cultural activities that are "tradition" thanks to the last right wing - far right government.

Bill C-309 is the law in question [1]. It should only affect "unlawful" assemblies, but I'd be interested to see what the functional criteria are, how much warning is appropriate, and whether a protest's status can be changed retroactively.

>Harper years

The Liberals were also supporters of this bill, including the current Prime Minister.