My faves:
5. Primal Fear
Actually, as a courtroom drama, Primal Fear is just a so-so movie. However, it gets pushed up a notch or two on the quality scale based almost exclusively on Edward Norton's stand-out debut performance. His switch on a dime acting, combined with his unfamiliarity with the viewing audience at the time is what, for me, primarily drove the twist ending of this film, & ultimately, help it to achieve it's intended purpose.
4. A Few Good Men
Yo, did anyone around here order a code red?
No, seriously.
I want the truth.
3. My Cousin Vinny
My favorite Joe Pesci movie, with a formula plot that works in the way that a good formula plot is supposed to work: a plotline with an unplausible situation, but the right combination of strikes at the chords of suspendibilty, along with a fair share of "smile-lined" humor.
Not to mention that Marissa Tomei steals a good part of the show & looks as hot as she ever has in any movie.
2. The Verdict
Paul Newman in an amazing court case drama written by David Mamet & superbly directed by Sidney Lemut. This triad of various veteran expertise & talent combine to produce a fight-the-system story of a man seeking justice against the advice of his closest colleague/partner, the mega-structure of the malpractice status quo, the will of a high priced large legal-firm, his own clients' wishes, and most of all, against his own inner demons.
1. 12 Angry Men
Okay, technically this isn't really a "courtroom" drama because the entire film happens in the jury-room. But let's face it, the plot's purpose is one that leads into that part which is most important of the courtroom process, the verdict.
Besides, 12 Angry Men is such a good movie, that, IMO, it simply blows the majority of every other film in this genre out of the water.
BTW, I still haven't seen To Kill A Mockingbird. If there is a thread around here about listing one's top must-see movie classics, for me, this would be the one.