A counterclaim is a retaliatory claim by a defendant against a plaintiff in a lawsuit included in the defendant's answer and intending to reduce the amount of the plaintiff's original claim against the defendant. Some states require the defendant to file a cross-complaint, which is a separate complaint that is part of the same lawsuit, rather than asserting a counterclaim in the answer. Federal courts require the defendant to state any asserted counterclaim to reduce damages in their answer or else it is barred from being considered.
