An affirmative defense is a type of defense in which the defendant seeks to avoid liability by introducing new evidence not addressed in the claims of the plaintiff's complaint. Such a defense must be raised in the defendant's answer, and because affirmative defenses require the assertion of facts beyond those claimed by the plaintiff, the defendant has the burden of proof for the defense. The burden of proof is typically lower than beyond a reasonable doubt. It can either be clear and convincing or preponderance of the evidence. An affirmative defense must be timely made by the defendant in order for the court to consider it, or else it is considered waived by the defendant's failure to assert it.