It doesn't.
Clownboy is simply saying that there are avenues for a redress of grievances.
How effective those avenues actually are is the big question.
To the best of my knowledge, the cop who applied the banned chokehold in the Garner case was not punished.
He's really, really sorry, though.
I am not in any manner supporting looting or arson in this comment. But having made that condition, "riots" that threaten the orderliness of "power" in such raw numbers and destructive force sometimes is the only thing likely to bring major change. The American Revolution was an extremely violent - and organized - "riot" in a sense, though became one very structured and more appearing then military.
It was riots that brought down the monarchy in France. Mob actions that often have the greatest effect. Yet the effect can be even by a few.
I read some time ago that the government had basically given farmers any loans they wanted, their family farms for generations as collateral. The economy turned south as did crop prices, and banks began a mass campaign of foreclosures and seizing all equipment. Then one day an old farmer, ordinary guy, wired the end of a 12 gauge barrel to the back of a banker's neck - and the protests at farms was growing - with growing concern the farmers were going to start shooting. The foreclosures stopped. Though certainly that old man went to prison.
The destruction, protests, political fall out, media attention, all will have effect as it motivates those in power and of wealth to act. The one thing that the most powerful and wealthy are vulnerable is to violence, the only threat they have. As long as people are docile, it is no threat. If they aren't, everything they have, their city, their wealth or even their own lives go at risk.
That sounds like advocacy of revolution, but it isn't. It is about the ying-yang balance of power. There should not be too much power in the hands of authority. There should not be too much power in the hands of the mob. Where is the balance?
When police can gang jump people merely for momentarily resisting just being questioned about something petty - and this resulting in violence against those citizens resulting in their deaths - the power is too shifted to authority. I do not mean Michael Brown. I mean Mr. Garner.
It is a question of power. If it goes too far one way or the other, the result will be counter power and often violently and destructively.