As we stated in Wickard [v. Filburn, 317 U. S. 111, 128–129 (1942)], “even if appellee’s activity be local and though it may not be regarded as commerce, it may still, whatever its nature, be reached by Congress if it exerts a substantial economic effect on interstate commerce.” Id., at 125. We have never required Congress to legislate with scientific exactitude. When Congress decides that the total incidence’ ” of a practice poses a threat to a national market, it may regulate the entire class. See Perez, 402 U. S., at 154–155 (quoting Westfall v. United States, 274 U. S. 256, 259 (1927) (“[W]hen it is necessary in order to prevent an evil to make the law embrace more than the precise thing to be prevented it may do so”)). In this vein, we have reiterated that when “ ‘a general regulatory statute bears a substantial relation to commerce, the de minimis character of individual instances arising under that statute is of no consequence.’ ” E.g., Lopez, 514 U. S., at 558 (emphasis deleted) (quoting Maryland v. Wirtz, 392 U. S. 183, 196, n. 27 (1968)).

  Wickard thus establishes that Congress can regulate purely intrastate activity that is not itself “commercial,” in that it is 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.

  Given the enforcement difficulties that attend distinguishing between marijuana cultivated locally and marijuana grown elsewhere, 21 U. S. C. §801(5), and concerns about diversion into illicit channels, we have no difficulty concluding that Congress had a rational basis for believing that failure to regulate the intrastate manufacture and possession of marijuana would leave a gaping hole in the CSA. Thus, as in Wickard, when it enacted comprehensive legislation to regulate the interstate market in a fungible commodity, Congress was acting well within its authority to “make all Laws which shall be necessary and proper” to “regulate Commerce . . . among the several States.” U. S. Const., Art. I, §8. That the regulation ensnares some purely intrastate activity is of no moment.

  Unlike those at issue in Lopez and Morrison, the activities regulated by the CSA are quintessentially economic. Economics” refers to “the production, distribution, and consumption of commodities.” Webster’s Third New International Dictionary 720 (1966). The CSA is a statute that regulates the production, distribution, and consumption of commodities for which there is an established, and lucrative, interstate market. Prohibiting the intrastate possession or manufacture of an article of commerce is a rational (and commonly utilized) means of regulating commerce in that product.

[T]he authority to enact laws necessary and proper for the regulation of interstate commerce is not limited to laws governing intrastate activities that substantially affect interstate commerce. Where necessary to make a regulation of interstate commerce effective, Congress may regulate even those intrastate activities that do not themselves substantially affect interstate commerce.

That simple possession is a noneconomic activity is immaterial to whether it can be prohibited as a necessary part of a larger regulation. Rather, Congress’s authority to enact all of these prohibitions of intrastate controlled-substance activities depends only upon whether they are appropriate means of achieving the legitimate end of eradicating Schedule I substances from interstate commerce.
  By this measure, I think the regulation must be sustained. Not only is it impossible to distinguish “controlled substances manufactured and distributed intrastate” from controlled substances manufactured and distributed interstate,” but it hardly makes sense to speak in such terms. Drugs like marijuana are fungible commodities. As the Court explains, marijuana that is grown at home and possessed for personal use is never more than an instant from the interstate market— . . . .

Whatever the specific theory of “substantial effects” at issue (i.e., whether the activity substantially affects interstate commerce, whether its regulation is necessary to an interstate regulatory scheme, or both), a concern for dual sovereignty requires that Congress’ excursion into the traditional domain of States be justified. That is why characterizing this as a case about the Necessary and Proper Clause does not change the analysis significantly. Congress must exercise its authority under the Necessary and Proper Clause in a manner consistent with basic constitutional principles.
. . . [T]hat authority must be used in a manner consistent with the notion of enumerated powers— — a structural principle that is as much part of the Constitution as the Tenth Amendment’s explicit textual command. Accordingly, something more than mere assertion is required when Congress purports to have power over local activity whose connection to an intrastate market is not selfevident.

  Relying on Congress'’ abstract assertions, the Court has endorsed making it a federal crime to grow small amounts of marijuana in one’s own home for one'’s own medicinal
use. This overreaching stifles an express choice by some States, concerned for the lives and liberties of their people, to regulate medical marijuana differently. If I were a California citizen, I would not have voted for the medical marijuana ballot initiative; if I were a California legislator I would not have supported the Compassionate Use Act. But whatever the wisdom of California'’s experiment with medical marijuana, the federalism principles that have driven our Commerce Clause cases require that room for experiment be protected in this case. For these reasons I dissent.

[I]n order to be "“necessary,"” the intrastate ban must be more than “a "reasonable means [of] effectuat[ing] the regulation of interstate commerce.”" Brief for Petitioners 14; see ante, at 19 (majority opinion) (employing rational-basis review). It must be “plainly adapted” to regulating interstate marijuana trafficking— — in other words, there must be an “obvious, simple, and direct relation” between the intrastate ban and the regulation of interstate commerce.

[N]either in enacting the CSA nor in defending its application to respondents has the Government offered any obvious reason why banning medical marijuana use is necessary to stem the tide of interstate drug trafficking. Congress'’ goal of curtailing the interstate drug trade would not plainly be thwarted if it could not apply the CSA to patients like Monson and Raich. That is, unless Congress’ aim is really to exercise police power of the sort reserved to the States in order to eliminate even the intrastate possession and use of marijuana.

  Veteran Supreme Court reporter Lyle Dennison has suggested that Justice Kennedy [voted to reverse in Raich because he] has a zero-tolerance approach to drugs. Justice Kennedy's deportment during oral argument supports that theory, but we will never know because he joined the majority opinion without comment. . . . How [Kennedy] reconciles his expressed support for the traditional law-enforcement role of the states with his joining what can only be described as the opposite view expressed by Justice Stevens only he can say. But he chose not to.

[T]he Court as an institution and the legal system as a whole have an immense stake in the stability of our Commerce Clause jurisprudence as it has evolved to this point. Stare decisis operates with great force in counseling us not to call in question the essential principles now in place respecting the congressional power to regulate transactions of a commercial nature. That fundamental restraint on our power forecloses us from reverting to an understanding of commerce that would serve only an 18th century economy, dependent then upon production and trading practices that had changed but little over the preceding centuries; it also mandates against returning to the time when congressional authority to regulate undoubted commercial activities was limited by a judicial determination that those matters had an insufficient connection to an interstate system.