Forensic rhetoric, as coined in Aristotle's On Rhetoric, encompasses any discussion of past action including legal discourse—the primary setting for the emergence of rhetoric as a discipline and theory. This contrasts with deliberative rhetoric and epideictic rhetoric, which are reserved for discussions concerning future and present actions respectively.
In contemporary times, the word forensic is commonly associated with criminal and civil law referring specifically to forensic science. It is important to note that the term forensic associated with criminal investigation exists because forensic (or judicial) rhetoric first existed.
An introduction of the three types of rhetoric (forensic, deliberative, and epideictic) occurs in Book I Chapter III of Aristotle's On Rhetoric. Discussion of forensic rhetoric is found in Book I, Chapters X–XV, outlined as follows:
Chapter 10: "Topics about Wrongdoing" asserts: "Let wrongdoing be defined as doing harm willingly in contravention of the law." Aristotle also defines three considerations of forensic rhetoric: 1. For what purposes persons do wrong 2. How these persons are mentally disposed 3. What kind of persons they wrong and what these persons are like.
Chapter 11: "Topics about Pleasure" categorizes pleasure as natural, not compulsive, and can be the cause of crime: gaining revenge, winning, or restoring honor.
Chapter 12: "Topics about Wrongdoers and Those Wronged" includes many features of both the wrongdoers and the wronged that relate to criminalities:
Wrongdoers: believe they will not be detected or punished, are likely to go unsuspected if their appearance is inconsistent with the charges (a weak man charged with assault), have either no enemy or many enemies.
Those who are wronged: have something the wrongdoer lacks, do not live cautiously, have never been wronged, or have been often wronged with no retaliation.
Chapter 13: "Topics about Justice and Injustice" discusses the law in two ways: specific (that which has been defined for each person) and common (that which is based on nature or common principle).