Tort Law: Under comparative negligence, if a defendant wants to establish that a co-defendant is responsible for more of the fault based on facts not pleaded by the plaintiff, the defendant must plead the new facts as an affirmative defense in their answer.

The Estate of Lasley sued Clemmer and Combined Trucking, Inc. (CT) for negligence. One of CT’s trucks caused traffic to stop on the I-5 freeway and Clemmer rear-ended Lasley’s stopped car, killing Lasley. The district court excluded evidence that Clemmer was driving while intoxicated because Lasley did not allege those facts. The Court of Appeals decided that evidence of Clemmer’s intoxication was relevant to the issue of apportionment of fault. The Supreme Court held that evidence of Clemmer’s intoxication was not relevant on the issues of causation, liability, or damages, but it was relevant to determine the degree of fault of both Clemmer and CT. Moreover, CT should have raised Clemmer’s intoxication as an affirmative defense in its answer. However, due to the unique circumstances in this case, the Court construed CT’s counter-claim for contribution as the equivalent of an affirmative defense because it put Lasley on notice of CT’s theory that Clemmer was intoxicated and therefore should have a higher degree of fault. The decision of the Court of Appeals was affirmed. Judgment of the circuit court was reversed, and the case was remanded.