The Sixth Circuit Court of Appeals’ recent opinion in Lyngaas v. Curaden AG (“ Lyngaas”), has important implications for federal class actions regarding personal jurisdiction and the use of non-admissible evidence to support class certification. In Lyngaas, a plaintiff brought a class action against Curaden AG, a Swiss entity, and its U.S. subsidiary, Curaden USA, for allegedly violating the TCPA. The basis for the plaintiff’s allegations were two unsolicited fax advertisements sent on behalf of Curaden USA to the plaintiff and 46,000 other individuals across the country. These advertisements did not mention Curaden AG. Curaden AG argued the district court lacked personal jurisdiction over it, while the plaintiff relied on an “alter ego” theory to support the exercise of personal jurisdiction. The district court rejected the “alter ego” theory but found that it had specific personal jurisdiction over Curaden AG on other grounds. The district court also granted class certification, rejecting Curaden’s argument that the plaintiff failed to support his motion for class certification with admissible evidence.