Fritz Lang was a director long fascinated by the themes of mob justice and kangaroo courts. In "Fury," Spencer Tracy is locked up in jail for a crime he didn't commit, but the local townspeople are so blinded by, ahem, fury, that they burn down the jail and Tracy is presumed dead and many of the townspeople are brought up on murder charges. The trial opens up many questions of who is culpable during a mob riot and what would happen if Tracy were actually alive and seeking revenge (dun dun DUN!).
"Young Mr. Lincoln"
Abraham Lincoln is best known as America's 16th president and inventor of the handheld mop-wringer, but did you know he was also a lawyer? John Ford's classic courtroom drama shows Lincoln in just that capacity, acting as a defense attorney for two young brothers accused of murder. Each one says he's guilty for fear of the other one hanging for the crime, but ol' Honest Abe gets to the truth of the matter in a legendary and highly dramatic fashion.
"Inherit the Wind"
Arguably the greatest trial film ever made doesn't show a murder trial or a child custody battle, but instead a court case over the origins of human life. If that sounds too ridiculous to be true, remember that "Inherit the Wind" is a fictionalized depiction of the famous Scopes Monkey Trial, in which a science teacher was placed on trial for teaching evolution. Unfortunately for fans of science, the movie is almost as relevant now as it ever was.
"…And Justice For All"
A fine example of both the courtroom drama and the Al Pacino freakout, "…And Justice For All" depicts a young, ethical defense attorney (Pacino) who is compelled to defend a corrupt judge on charges of rape. The aforementioned freakout in which Pacino gives his famous "you're out of order!" speech is justifiably famous, and a great example of speaking truth to power. He is promptly held in contempt of court and thrown out.
Another contender for "greatest courtroom drama of all time" has Paul Newman as a drunken screwup of an attorney, who somehow gets a hold of a huge civil case which could hold corrupt hospital managers responsible for a serious case of medical neglect which left a woman completely incapacitated for life. It would be a tragedy to reveal the titular verdict here, but suffice it to say that no fan of trial films should miss this one.