In North River Ins. Co. v. Leifer, the United States Court of Appeals for the Second Circuit determined that a "prior knowledge" exclusion in a professional liability insurance policy excused the insurer from its duty to defend against malpractice claims brought against its insured. In so holding, the Second Circuit concluded that the insured failed to disclose facts and circumstances to its insurer that it knew or should have known could result in a future malpractice claim.