1- People have a right to "peaceably" assemble under the first amendment to the US Constitution.
2- When their assembly is NOT peaceful, it is unlawful.
3- The US Supreme court has repeatedly held that blocking traffic, footpaths/sidewalks, business entrances, etc. are NOT considered peaceful, and are therefore unlawful.
4- These protestors were blocking a path.
5- The protestors were warned of the unlawfulness of their actions.
6- The protestors were warned they would be sprayed.
7- The protestors got sprayed.
8- Occupy jail