From the Document: "Clause 3 of Article I Section 8 of the U.S. Constitution, generally referred to as the 'Commerce Clause,' is one of the enumerated powers under which Congress may legislate. The clause states that Congress shall have the power 'to regulate Commerce with foreign Nations, and 'among the several States,' and with the Indian Tribes.' Congress may only act pursuant to its enumerated powers. 'Gregory v. Ashcroft,' 501 U.S. 452, 460 (1991). The scope of those powers informs the kinds of laws Congress may enact. Congress frequently invokes the Commerce Clause, and specifically the so-called Interstate Commerce Clause that addresses commerce 'among the several states,' as the authority for a variety of legislation regulating domestic activity. The Supreme Court has often interpreted the scope of Congress's authority to regulate interstate commerce under the Commerce Clause, and that interpretation has evolved over time. [...] Through most of the latter half of the twentieth century, the Court adopted a more expansive conception of Commerce Clause authority, allowing Congress to regulate activities that largely occurred intrastate if there was a rational basis to believe the activity, in aggregate, would have a substantial effect on interstate commerce. Beginning in the 1990s, the Court issued several opinions confirming the existence of outer limits to congressional power under the Commerce Clause and striking down laws that transgressed those limits by regulating certain purely intrastate, noneconomic activities."
CRS In Focus, IF11971
Congressional Research Service: https://crsreports.congress.gov/