Does the plaintiff or the defendant have the burden of proof in an affirmative defense?

Expert Answers
crmhaske eNotes educator| Certified Educator

An affirmative defense requires two things to be true:

  1. The defendant does not deny the allegations of the plaintiff, hence the term affirmative.  The defendant affirms that the plaintff's claims are true.
  2. The defendant must present new evidence to support the affirmative defense to the court that if true would be "legally sufficient to excuse the defendant."

In a civil case, the burden of proof lies with the plaintiff, not with the defendant. Yet a defendant who is affirmatively defending their action takes on the burden to prove their affirmative evidence "credible.".

In civil cases, the plaintiff has the burden of proving his case by a preponderance of the evidence. (Cornell Law School)

That said, the burden of proof may shift to the defendant if the defendant raises a factual issue in defense to the plaintiff's claims. (Cornell Law School about Nolo's Plain-English Law Dictionary)