In response to Fritz's post regarding OJ and Peterson; I would reply they certainly are capable of not convicting Scott Peterson. Does that mean they are screwing up, maybe not. As a young lawyer the one thing I have learned is that it does not matter what I know, it matters what I can convince a fact-finder (i.e. jury or judge depending on the circumstance).
There is a mountain of literature on jury selection most of which really is about settling the nerves of lawyers in an effort to make them believe they are taking the correct efforts to maximize their chance of winning. This is much the same as a card counter in a casino. The bottom line of it all is that you never know what a jury is going to do. We all know taht OJ was released because the jury was making a statement and had nothing to do with guilt or innocence. The jury can do that without recourse in this circumstance. (If they were to convict to make a statement the judge could simply nullify the verdict -- another issue for another time).
The modern courtroom is as much about making connections as it is about facts and law. This why some attorneys can charge such high fees. Endear yourself to the factfinder, present your case, give the jury someone to blame besides your client (Plan B of the "Practice" but common practice in every courtroom coast to coast) and a few other tricks. The burden is on the state to prove beyond a reasonable doubt that the person before the court committed the crime. What is a reasonable doubt? No one really knows and some judges who try to define it for a jury are overruled for their efforts. Consensus seems to be alot of proof. Maybe I am being a bit tounge and cheek.
But the state has a huge burden in attaining a conviction and there are many reasons why they may not get a conviction. Trying someone in the media is much different than in a courtroom. The reason these high priced attorneys can demand so much money is that they are excellent at working the system to their end. When Allen Iverson was on trial here in Philadelphia, I was working for the Judge that presided over the case. It was remarkable to see his lawyer work, he was very subtle and methodic but when he was done he had presented his case in such a way that it was hard to argue with him. It was remarkable. The Prosecutors are good as well but the deck is stacked against them in terms of evidence, burden of proof and presumptions ... it's much better than tie goes to the runner.
Bottom line, the system on the criminal side is summed up in this one phrase... "it is better to let ten guilty men go free than convict one innocent man."