You can get pissed about the verdict because you don't think it's justice. You can even get mad at one of the defense lawyers who pretty much called everyone dumbasses for doubting him and for believing in the media hype. However, you cannot blast the justice system. Our constitution is something that separates us from 3rd world countries far away. In the US criminal justice system, the prosecution must prove the defendant is guilty without a shadow of a doubt. They have to destroy any ounce of doubt that there was any other way the crime was committed. In this case, they didn't. Now, this is not to say that Casey is a upstanding member of community. I don't believe going out, partying, and competing in "hot body" contests is the itinerary of a parent who doesn't know the whereabouts of their young child. However, you cannot fault her for hiring the best lawyers to defend her case. Simple fact, if she is actually guilty, the prosecution did a piss poor job of showing it. Even if you have loads of evidence, if you don't connect the dots and show 12 members of the jury that Casey Anthony is the ONLY person to be involved and the chloroform and duct tape were the ONLY way Caylee was murdered, then you have upheld your end of the bargain to the tax payers in Orlando.
If you don't like it, move to a country without a real constitution and see that, there, you will be found guilty just because they THINK you did something....