In a civil case, an answer is the defendant's written response to the plaintiff's complaint. It must be filed within a specified period of time, and it either admits to or (more typically) denies the factual or legal basis for liability. Some states allow an answer to state a lack of knowledge as to whether a particular allegation is true or false. The answer may also include "affirmative defenses" including allegations which contradict the complaint or contain legal theories (like "unclean hands," "contributory negligence" or "anticipatory breach") which are intended to undercut the claims in the complaint. If the defendant fails to file an answer, the plaintiff usually wins by default. There are rules of evidence which govern the formalities and time period required in filing an answer. The answer is usually filed along with a proof of service of the same upon the other parties to the action.
