What is the subject matter jurisdiction of the federal district court in relation to RICO claims?

Subject matter jurisdiction of the district court turns first on the question of RICO jurisdiction. ² RICO is pivotal insofar as none of the remaining claims is independently removable because of obstacles presented by the derivative jurisdiction doctrine, statutory bars, or the plain absence of a federal claim. Following the submission of this case, we resolved the difficult question of whether federal courts have concurrent or exclusive jurisdiction over RICO claims by ruling that such jurisdiction is concurrent. Lou v. Belzberg, 834 F.2d 730, 739 (9th Cir.1987).