Collectively, the attorneys representing a defendant and any laypeople assisting them in their efforts, particularly in a criminal trial. In litigation, generally a factual denial or an assertion of facts or law that counters or negates a claim made by the other party. See also self defense. affirmative defense. A statement of fact in a responsive pleading that, if true, has the effect of canceling or rendering ineffective a claim of the other party. For example, the truth of an allegedly def...