Williams Pipe Line Company, a Delaware Corporation v. Empire Gas Corporation, a Missouri Corporation

BALDOCK, Circuit Judge.

Under the Interstate Commerce Act, pipeline common carriers are required to establish rates and practices related to the transportation they provide, and file a tariff containing the rates and practices with the Federal Energy Regulatory Commission (“FERC”). 42 U.S.C. § 7172(b), 49 U.S.C. §§ 60501, 10501(a), 10762(a). A filed tariff rate or practice “governs the legal relationship between” a carrier and its shippers, unless subsequently invalidated. See Maislin Indus., U.S. v. Primary Steel, Inc., 497 U.S. 116, 126, 128, 110 S.Ct. 2759, 2765, 2766-67, 111 L.Ed.2d 94…