Represented a clearing firm in a FINRA arbitration filed by customers of a broker-dealer for which the clearing firm provided services. Four groups of customers each brought FINRA arbitrations against the firm seeking to recover investor losses. The clearing broker-dealer processed, but had no role in originating, trading activity that the SEC deemed fraudulent in a related proceeding. The clearing firm contested the arbitral jurisdiction of FINRA over the proceedings based on the fact that the claimants were not "customers" of the clearing firm, had no arbitration agreement with it, and as such, could not compel arbitration. First, we tried to exercise a little used provision in the FINRA Code of Arbitration Procedure to urge the Director of Arbitration to deny access to the forum. Although those efforts were unsuccessful, they laid the groundwork for a more direct legal challenge in federal district court. In this case, the claimant agreed to voluntarily dismiss the arbitration after we filed the jurisdictional challenge.