Held: Congress’ Commerce Clause authority includes the power to prohibit the local cultivation and use of marijuana in compliance with California law. Pp. 10–33.
(a) For the purposes of consolidating various drug laws into a comprehensive statute, providing meaningful regulation over legitimate sources of drugs to prevent diversion into illegal channels, and strengthening law enforcement tools against international and interstate drug trafﬁcking, Congress enacted the Comprehensive Drug Abuse Prevention and Control Act of 1970, Title II of which is the CSA. To effectuate the statutory goals, Congress devised a closed regulatory system making it unlawful to manufacture, distribute, dispense, or possess any controlled substance except as authorized by the CSA. 21 U. S. C. §§841(a)(1), 844(a). All controlled substances are classiﬁed into ﬁve schedules, §812, based on their accepted medical uses, their potential for abuse, and their psychological and physical effects on the body, §§811, 812. Marijuana is classiﬁed as a Schedule I substance, §812(c), based on its high potential for abuse, no accepted medical use, and no accepted safety for use in medically supervised treatment, §812(b)(1). This classiﬁcation renders the manufacture, distribution, or possession of marijuana a criminal offense. §§841(a)(1), 844(a). Pp. 10–15.
(b) Congress’ power to regulate purely local activities that are part of an economic “class of activities” that have a substantial effect on interstate commerce is ﬁrmly established. See, e. g., Perez v. United States, 402 U. S. 146, 151. If Congress decides that the “‘total incidence’” of a practice poses a threat to a national market, it may regulate the entire class. See, e. g., id., at 154–155. Of particular relevance here is Wickard v. Filburn, 317 U. S. 111, 127–128, where, in rejecting the appellee farmer’s contention that Congress’ admitted power to regulate the production of wheat for commerce did not authorize federal regulation of wheat production intended wholly for the appellee’s own consumption, the Court established that Congress can regulate purely intrastate activity that is not itself “commercial,” i. e., not produced for sale, if it concludes that failure to regulate that class of activity would undercut the regulation of the interstate market in that commodity. The similarities between this case and Wickard are striking. In both cases, the regulation is squarely within Congress’ commerce power because production of the commodity meant for home consumption, be it wheat or marijuana, has a substantial effect on supply and demand in the national market for that commodity. In assessing the scope of Congress’ Commerce Clause authority, the Court need not determine whether respondents’ activities, taken in the aggregate, substantially affect interstate commerce in fact, but only whether a “rational basis” exists for so concluding. E. g., Lopez, 514 U. S., at 557. Given the en-