The purpose of a grand jury is to determine whether there is probable cause to file charges, not to determine guilt or innocence. That means the DA puts forward the best possible case for prosecution. They don't throw everything at the grand jury and let them decide what happened; that's the job of a trial (petit) jury. Only really bad cases -- ones where the grand jury feels that under no view of the facts could the person be found guilty -- result in no indictment. For more on this, here's Tumblr commentary by an assistant state's attorney in Baltimore:
http://lindentreeisle.tumblr.com/post/103508665696/justice4mikebrown-ive-noticed-some-people-are
A more extensive post by another attorney reblogged by the same assistant state's attorney:
http://lindentreeisle.tumblr.com/post/103600053421/why-the-ferguson-grand-jury-was-completely
Here's an analysis of the (non-existent) cross-examination of Darren Wilson:
http://lindentreeisle.tumblr.com/post/103647444636/t-ii-civil-rights-attorney-msnbc-legal-analyst
Also, the grand jury was composed of nine whites and three African-Americans -- two women and one man. Nine votes are required to indict.
A masterpost with links about the case:
http://ponyregrets.tumblr.com/post/103635921889/rosethomass-if-you-like-me-get-so-angry-when
Even assuming -- and given the information and video in the above masterpost, that's an iffy assumption -- Michael Brown shoplifted cigars, that is neither the grounds for the death penalty (which is in effect what happened here) or for shooting a fleeing suspect, who has to have committed a violent felony, see masterpost. FFS, the Supreme Court has held that the death penalty is only constitutionally permissible in homicide cases.
Ex-NBA star Charles Barkley wrote a book titled Who's Afraid of a Large Black Man? According to his grand jury testimony, Darren Wilson is. Black men are automatically presumed to be dangerous criminals, so the fear of them is considered justified and reasonable. Not much will improve until people lose that ingrained fear. Want more proof? White men get away with far worse without being shot by the police.
And as for the argument that any violence that's occurred invalidates any of this? (And as far as I know, it's been property damage that's occurred, not looting.) In March of 1968, Martin Luther King, Jr. said this:
I am still committed to militant, powerful, massive, non*-violence as the most potent weapon in grappling with the problem from a direct action point of view. I'm absolutely convinced that a riot merely intensifies the fears of the white community while relieving the guilt. And I feel that we must always work with an effective, powerful weapon and method that brings about tangible results. But it is not enough for me to stand before you tonight and condemn riots. It would be morally irresponsible for me to do that without, at the same time, condemning the contingent, intolerable conditions that exist in our society. These conditions are the things that cause individuals to feel that they have no other alternative than to engage in violent rebellions to get attention. And I must say tonight that a riot is the language of the unheard. And what is it America has failed to hear? .... It has failed to hear that the promises of freedom and justice have not been met. And it has failed to hear that large segments of white society are more concerned about tranquility and the status quo than about justice and humanity.
Source here.
If Martin Luther King, Jr. were alive today, he'd be able to make the same speech, except instead of pointing to poverty he'd point to police misconduct and a siege mentality that assumes that black folks are up to no good while white folks get the benefit of the doubt. I'd also like to point out that there's no big outcry when senseless property damage happens after a city's sports team loses. That's considered par for the course.