No supplemental jurisdiction? Then nothing else either.

After the plaintiff voluntarily dismissed the federal securities claims that justified removal, the district court retained jurisdiction over the case based on supplemental jurisdiction and granted a motion to compel arbitration. The Fifth Circuit rejected the supplemental-jurisdiction argument and vacated the motion to compel: “All of SJAP’s claims against Cigna arise from or concern the In-Network Agreement and the resulting business relationship. SJAP’s federal claim against the Insight Defendants, by contrast, was based on SJAP’s purchase of securities from Insight as part of the Lab Operating Agreement, a completely separate contract that had nothing to do with Cigna that was consummated several years before the events giving rise to SJAP’s claims against Cigna. Other than SJAP’s vague assertion that Insight and the Cigna Affiliates previously ‘had a lengthy and sordid relationship’ that resulted in an undisclosed settlement agreement, the operative complaint when the case was removed demonstrated no connection between Cigna and the Insight controversy, let alone the specific federal security claim that conferred original jurisdiction on the district court.” SJ Associated Pathologists v. Cigna Healthcare of Texas, No. 20-20188 (July 6, 2020) (emphasis added).