THIS CASEBOOK contains a selection of U. S. Court of Appeals decisions that analyze, interpret and apply Commerce Clause doctrine. * * * Implicit in the constitutional allocation of the "Power ... To regulate Commerce ... among the several States," U.S. Const. art. I, § 8, cl. 3, to the federal government is a corollary "constraint on the power of the States to enact legislation that interferes with or burdens interstate commerce." Brown v. Hovatter, 561 F.3d 357, 362 (4th Cir. 2009). This doctrine, known as the "dormant" commerce clause, "is driven by concern about economic protectionism" and seeks to prevent state "regulatory measures designed to benefit in-state economic interests by burdening out-of-state competitors." Id. at 363 (quoting Dep't of Revenue of Ky. v. Davis, 553 U.S. 328, 337-38, 128 S.Ct. 1801, 170 L.Ed.2d 685 (2008)). * * * The principle against extraterritoriality as it relates to the dormant commerce clause is derived from the notion that "a State may not regulate commerce occurring wholly outside of its borders." Star Sci., Inc. v. Beales, 278 F.3d 339, 355 (4th Cir. 2002) (citing Healy v. Beer Inst., 491 U.S. 324, 335-36, 109 S.Ct. 2491, 105 L.Ed.2d 275 (1989); Brown-Forman Distillers Corp. v. N.Y. State Liquor Auth., 476 U.S. 573, 582-83, 106 S.Ct. 2080, 90 L.Ed.2d 552 (1986); Edgar v. MITE Corp., 457 U.S. 624, 642-43, 102 S.Ct. 2629, 73 L.Ed.2d 269 (1982) (plurality opinion)). The principle "reflect[s] the Constitution's special concern both with the maintenance of a national economic union unfettered by state-imposed limitations on interstate commerce and with the autonomy of the individual States within their respective spheres." Healy, 491 U.S. at 335-36, 109 S.Ct. 2491 (footnote omitted). A state law violates the extraterritoriality principle if it either expressly applies to out-of-state commerce, see Carolina Trucks & Equip., Inc. v. Volvo Trucks of N. Am., Inc., 492 F.3d 484, 491-92 (4th Cir. 2007), or has that "practical effect," regardless of the legislature's intent, Star Sci., 278 F.3d at 355. Association for Accessible Medicines v. Frosh, 887 F. 3d 664 (4th Cir. 2018)