Tafflin and other holders (plaintiffs) of unpaid certificates of deposit (CDs) sued Levitt and other officials (defendants) of the failed bank that did not pay the CDs. The plaintiffs brought suit in federal district court under the Racketeer Influenced and Corrupt Organizations Act (RICO), 28 U.S.C. § 1961-68. The defendants filed a motion to dismiss the case, due to pending state-court litigation based on the same claim. The district court dismissed the complaint, ruling that it should abstain from hearing the action in deference to the pending litigation in Maryland state court. The United States Court of Appeals for the Fourth Circuit affirmed. The United States Supreme Court granted certiorari.