Quote from nonlinear5:
The (remaining) freedoms that we have in the United States are based on the presumption of innocence, not on the presumption of guilt. When I walk (or jog, or skip) in any neighborhood, I don't owe any explanation to any "good citizens" as to what I am doing here, or why I am dressed in a certain way. If the "good citizens" start following me, I'd perceive it as a threat and say, "Fuck off, you creeps".
The burden of proof is on the police to have a reasonable suspicion that I am up to some illegal activity, in order for them to stop and question me. And yes, okay, the neighborhoods have the right to form whatever "militia" that the'd like, but again, I don't owe them any explanation unless there is a clear intent on my part to break the law. There wasn't anything like that in the case under the discussion.
Imagine a country (or a neighborhood) where this concept of presumption of innocence is substituted with the presumption of guilt. Would that make any neighborhoods safer? Hell, no. You'd be afraid to go anywhere, because any psycho with a gun would be entitled to follow you, stop you, question you, and kill you, if you show any signs of human dignity.