I just want to jump in here and comment on the use of pepper spray on protestors, since as a newspaper photojournalist I've seen lots of similar protests. This isn't addressing the race of the protesters directly.
- Cops give a lawful order for protestors to remove themselves from the area, warning they will be removed by force if they don't comply with the order.
- Protestors refuse, sit and join hands, etc.
- Cops weight their options, deciding that laying hands on the protestors to forcibly remove them has a very real chance of injuring protestors and cops. Lots of factors go into this tactical decision: how big is the crowd, are their violent elements among them, are there enough officers and holding facilities to detain the protestors or do they just need to be dispersed...etc.
- Cops then decide to use non-lethal pepper or OC spray to cause pain, but no physical injury, to the protestors to compel them to leave without having to go hands on and possibly injure someone.
I understand to the naive this may seem a "brutal" tactic, but what would you have our law enforcement officers do? Ask nicely and then give up when the protestors say no? Being sprayed with non-lethal pepper spray, which every officer has endured during training, is not the same as a bullet to the head. The protestors are responsible for pushing they authorities hand by refusing a lawful order. The cops have to figure out the move them as safely as possible to comply with the law.