The first teachers of oratory were the ancient Greeks and Romans, namely Aristotle and Cicero. When they were classifying "kinds" of oratory, they termed the kind of argument used in a court of law to prove or disprove past events "forensic" argumentation. Centuries later while universities were still teaching all the forms of argument, students decided to take it to the competitive level and began debating for sport in an activity they named "forensics." Today forensics includes competitive dramatics and public speaking.
In addition, the science that has the goal of finding evidence to be used in court-of-law arguments is termed "forensic science."