The Murri Affair (1974)

Based on a true incident, this tells the story of a troubled young man who kills his sister's reactionary, violent, abusive husband and is eventually arrested for the murder. However, the dead husband happened to be a member of the Italian nobility, and the trial starts to turn into more of a prosecution of the defendant's socialist politics and the activities of his father, a well-known liberal social reformer, than of the actual crime.