Procedural Inaccuracies

Ok, so I'm watching this movie right now and it's very good but I feel hesitant about calling it great because it takes a few serious liberties with the judicial process. The first one that comes to mind is the scene where Spencer Tracy cross examines the opposing counsel. This is simply ludicrous. I'm in law school and while I know never to say never when it comes to what can happen in courtroom, there are very clear evidentiary and ethical rules prohibiting a lawyer from being cross examined on his own case. This basically means that the lawyer is testifying against his own client! The notion is laughable even if you aren't in law school. Just think about it. The only thing I can think of is, given the sheer uniqueness of the crime and subject matter of the case, maybe some judge would allow it thinking that such a unique case required special rules but it would be immediately overturned on appeal. Secondly, and perhaps more fundamentally, they weren't even in federal court. This they mentioned in the movie so I don't put too much emphasis on it, but Dick York was being charged with violating a law. He clearly violated the law and a criminal court couldn't find any other way. His only out would be to have the law's validity challenged and the validity of that law could only be challenged in federal court, certainly not criminal court. I'm surprised that for such a high profile movie, the studio didn't care to hire even a law student like myself to give the script a once over.