“to extend federal power to virtually all human activity”

What is absolutely clear, affirmed by the text of the 1789 Constitution, by the Tenth Amendment ratified in 1791, and by innumerable cases of ours in the 220 years since, is that there are structural limits upon federal power—upon what it can prescribe with respect to private conduct, and upon what it can impose upon the sovereign States. Whatever may be the conceptual limits upon the Commerce Clause and upon the power to tax and spend, they cannot be such as will enable the Federal Government to regulate all private conduct and to compel the States to function as administrators of federal programs.

SCALIA, KENNEDY, THOMAS, and ALITO, JJ., dissenting