The Rail Passenger Service Act of 1970 (RPSA), 49 U.S.C. § 24101 et seq., created the National Railroad Passenger Corporation, also known as Amtrak, as part of an effort to revitalize passenger-rail service. Congress expressly created Amtrak as a for-profit corporation and provided that Amtrak’s board of directors was to be appointed by the president of the United States. The RPSA relieved struggling railroad companies of the burden of providing intercity passenger service. In return, the railroad companies consented to conditions that included giving Amtrak priority over freight trains in track access. Subsequently, in § 207 of the Passenger Rail Investment and Improvement Act of 2008 (PRIIA), 49 U.S.C. § 24101, Congress attempted to give joint authority to Amtrak and the Federal Railroad Administration (FRA) (defendant), an agency in the United States Department of Transportation (defendant), to create performance measures for intercity passenger trains. Along with enforcement measures in § 213 of the PRIIA, § 207 enhanced Amtrak’s statutory priority over other trains. After Amtrak and the FRA submitted their jointly prepared performance standards for public comment, the Association of American Railroads (AAR) (plaintiff) and other groups criticized the standards as unduly burdensome. AAR brought suit against the defendants, arguing that the PRIIA’s delegation of joint regulatory authority to Amtrak was unconstitutional. The district court granted summary judgment in favor of the defendants. AAR appealed.