To those who are saying Brown was being stopped for jaywalking:
Wilson noticed Brown was walking in the street and told him to walk on the sidewalk. Brown was ignoring Wilson's orders and began to aggressively resist him without reasonable provocation. The reason that Wilson turned the confrontation into something more was due to the aggressive resistance. He didn't just fly out of his car with a spray of bullets on an innocent apologetic boy who wasn't on the sidewalk.
Pursuing someone from jaywalking across a street that isn't even busy is a pretty unjustifiable reason to provoke someone even if you are a cop. That's something you just tell someone not to do, considering Brown was already making his way to the sidewalk.
And I'm wondering just what aggressive resistance an unarmed person could be capable of from a distance away.
There's quite a history of Darren Wilson's aggression in the past that would influence excessive force.