As most trials do, the Trayvon Martin case involves the clash of two perspectives. Martin's perspective clashed with Zimmerman's, with deadly results. From Martin's perspective, he was being following by a "creepy *ss cracker" (Trayvon's words). From Zimmerman's perspective, he was keeping an eye on a dangerous stranger who looked like he was "on drugs or something" (Zimmerman's words). Both probably were right.
Martin found Zimmerman to be creepy. The prosecution, which managed to prove little else in the case, might just have raised a jury issue on Zimmerman's creepiness. Finding both the law and the facts arrayed against proving the crime they had charged, the prosecutors (with assists from the judge) resorted to putting Zimmerman's character on trial. They portrayed Zimmerman, with at least some success, as a frustrated cop wannabe on a power trip. Maybe he was. One could understand why Martin found being followed by such a man to be "creepy."
From Zimmerman's perspective, Zimmerman thought he was keeping an eye on a dangerous stranger wandering around in his neighborhood. He may have been right. While the jury didn't get to hear this, we know that Trayvon was outside his home neighborhood at the time because he was on his third suspension from school, this time for drug possession. An earlier school suspension for writing obscenity on a locker also involved a search of his backpack which turned up a watch, a bag of women's jewelry, and a "burglary tool" i.e. a screwdriver that Trayvon claimed belonged to a friend whom he refused to identify. We also know that Trayvon bragged about engaging in (and winning) multiple fights and that he was seeking to obtain a firearm. Martin's brags about his macho exploits caused his friend to text Trayvon some good advice: "Boy don't get one planted in ya chest." Tragically, that wise advice went unheeded. Finally, and the jury was allowed to hear this part, Zimmerman's observation that Martin appeared to "on drugs or something" was correct -- marijuana (the very substance he had been suspended from school for possessing) was in his system at the time. In summary, contrary to the picture painted by the media, Trayvon was not a young man that you would want to meet in a dark alley, yet that is pretty much what Zimmerman did.
So what happened when these two perspectives clashed? The overwhelming evidence indicates that Martin confronted Zimmerman and beat him while Zimmerman screamed for help until Zimmerman finally shot Martin to death. So what would "justice" look like when the creepy cop wannabe meets the young punk thug? Only Heaven knows for sure. Our criminal system cannot make "justice" out of these circumstances, and it doesn't even try.
What our criminal justice system does is draw some bright lines that the creepy cracker and the young thug must not cross in their interactions with each other. Zimmerman felt threatened by seeing Martin wandering through his neighborhood, but even assuming that Martin was the dangerous figure Zimmerman thought he was, there is nothing illegal about a young thug wandering through a gated community. Martin crossed no legal line by being there. Similarly, Martin may have been creeped out by being watched by Zimmerman. But, again, Zimmerman's watching Martin crossed no legal line. Those who are clamoring for Zimmerman's head must be doing so because they think it SHOULD be illegal for a private citizen to be armed while keeping an eye on a stranger in his neighborhood, but it's not, at least not there.
The legal lines designed to allow the creepy cracker and the young thug to coexist were crossed when the first punch was thrown. The jury apparently thought that punch was thrown by Martin, and the evidence amply supports that conclusion. So Zimmerman was found "not guilty" beyond a reasonable doubt, which clearly was the correct legal result. Was it "justice"? I'm sure it doesn't feel like justice to Martin's family and friends, but it's the best our criminal legal system can do.