Free (P) filed suit in Louisiana state court alleging that Abbott Laboratories (D) and others conspired to fix infant formula prices. D filed for themselves and a class of Louisiana consumers. D removed to federal court, and P moved for a remand. The federal district court granted the remand as it held that it lacked federal question jurisdiction and that it had diversity jurisdiction over only P's claims and not over claims of other members of the class. The district court then declined to exercise supplemental jurisdiction because the claims raised novel issues of state law. D appealed and sought mandamus to vacate the court order remanding to state court.