Home > West's Encyclopedia of American Law > Affirmative Defense

A new fact or set of facts that operates to defeat a claim even if the facts supporting that claim are true.

A plaintiff sets forth a claim in a civil action by making statements in the document called the complaint. These statements must be sufficient to warrant relief from the court. The defendant responds to the plaintiff's claims by preparing an answer in which the defendant may deny the truth of the plaintiff's allegations or assert that there are additional facts that constitute a defense to the plaintiff's action. For example, a plaintiff may demand compensation for damage done to his or her vehicle in an automobile accident. Without denying responsibility for the accident, the defendant may claim to have an affirmative defense, such as the plain-tiff's contributory NEGLIGENCE or expiration of the