There was the process. There was the evidence. There was, unexpectedly, a synergy of the two. It was not only theatre to appease the critical demands of the angry locals, but one carefully orchestrated to make sure that there would be standing ovation at the end.
Many have scratched the surface of the grand jury proceeding that returned no indictment of Darren Wilson for the killing of Michael Brown, concluding that it was a sham, never meant to indict but to create the show that quiets the maddening crowd. They think this is an epiphany.
Others have noted that this isn't lawful, as the prosecutor can't present a case to the grand jury in which he doesn't believe, and to do so only to silence demands is unethical (they call it unlawful, but they must be forgiven such minor imprecision). As was already noted, we are a lazy and ignorant people when it comes to the processes of government. Perhaps naïve should be added to the list.
Much of what our government does serves the appearance of lawfulness without its substance. This is the Lie, and still the groundlings can't see it. Yes, it was a show. Yes, it was improper. Yes, it was done to quiet demands for blood. Yes, this is all very wrong. So what? What the hell do you think you can do about? They play a game that perpetuates the status quo, and the handful of you who realize it's wrong think you've discovered gold. Tomorrow, you will go back to playing video games and care nothing about the next wrong. Hell, you won't even know it happened if it smacked you upside the head.
If you had the capacity to dig deeper, you would realize that this is mundane manipulation. It happens all the time, but you're just too lazy and ignorant to realize it. The one time you stumble upon it, you're shocked and outraged. This is WRONG!, you scream.