A "protest" that prevents people from crossing a border or shuts down a city isn't a protest. It is hostage-taking.

The US First amendment has some good language on this: the people have a right to peaceably assemble, and to petition the government for a redress of grievances. Imposing a blockade does not qualify. If they just sit in front of Parliament and hold up signs and shout, but don't impede anyone going about their business, then they have a right to make their voices heard.

But what about (some other protest)? Civil rights protesters are usually ordered to disperse after a short time and get arrested if they don't. Sometimes they engage in civil disobedience, but they can be arrested if they do that.

The trick is to categorize protestors as "domestic terroists", despite having not done any extreme violent actions, as the Canadian government seems to be doing here.