This movie is a classic courtroom thriller with an excellent, cozy mystery style resolution. It’s clever and surprising in all the right ways, and the ending is Hitchcockian in its drama while being more Film Noir in its style. For period courtroom dramas you can’t do much better than this.
Closest comparison: It’s like The Mysterious Affair At Styles by way of Anatomy of a Murder.
Setting: Courtroom Drama
Plot: Cozy Mystery
Tone: Noir Thriller