I think the best lessons "Petrocelli" teaches us are that 1) things aren't always as they seem, and 2) there's a good reason to presume a person innocent until proven guilty - because he just might be innocent, after all. This is a cast that worked very well together, and the writing, too, was excellent. I liked the fact that we would see the crime being committed from different perspectives. I don't know if "Petrocelli" was the first show to ever do that, but it sure kept me tuned in every week. It would be wonderful if TV Land would run this series again.
