To quote the great Clarence Thomas
Respondents Diane Monson and Angel Raich use marijuana that has never been bought or sold, that has never crossed state lines, and that has had no demonstrable effect on the national market for marijuana. If Congress can regulate this under the Commerce Clause, then it can regulate virtually anything—and the Federal Government is no longer one of limited and enumerated powers.
Respondent's local cultivation and consumption of marijuana is not "Commerce ... among the several States."
[...]
Certainly no evidence from the founding suggests that "commerce" included the mere possession of a good or some personal activity that did not involve trade or exchange for value. In the early days of the Republic, it would have been unthinkable that Congress could prohibit the local cultivation, possession, and consumption of marijuana.
[...]
If the Federal Government can regulate growing a half-dozen cannabis plants for personal consumption (not because it is interstate commerce, but because it is inextricably bound up with interstate commerce), then Congress' Article I powers – as expanded by the Necessary and Proper Clause – have no meaningful limits. Whether Congress aims at the possession of drugs, guns, or any number of other items, it may continue to "appropria[te] state police powers under the guise of regulating commerce."
[...]
If the majority is to be taken seriously, the Federal Government may now regulate quilting bees, clothes drives, and potluck suppers throughout the 50 States. This makes a mockery of Madison's assurance to the people of New York that the "powers delegated" to the Federal Government are "few and defined", while those of the States are "numerous and indefinite."
emphasis on the bold being mine
Respondents Diane Monson and Angel Raich use marijuana that has never been bought or sold, that has never crossed state lines, and that has had no demonstrable effect on the national market for marijuana. If Congress can regulate this under the Commerce Clause, then it can regulate virtually anything—and the Federal Government is no longer one of limited and enumerated powers.
Respondent's local cultivation and consumption of marijuana is not "Commerce ... among the several States."
[...]
Certainly no evidence from the founding suggests that "commerce" included the mere possession of a good or some personal activity that did not involve trade or exchange for value. In the early days of the Republic, it would have been unthinkable that Congress could prohibit the local cultivation, possession, and consumption of marijuana.
[...]
If the Federal Government can regulate growing a half-dozen cannabis plants for personal consumption (not because it is interstate commerce, but because it is inextricably bound up with interstate commerce), then Congress' Article I powers – as expanded by the Necessary and Proper Clause – have no meaningful limits. Whether Congress aims at the possession of drugs, guns, or any number of other items, it may continue to "appropria[te] state police powers under the guise of regulating commerce."
[...]
If the majority is to be taken seriously, the Federal Government may now regulate quilting bees, clothes drives, and potluck suppers throughout the 50 States. This makes a mockery of Madison's assurance to the people of New York that the "powers delegated" to the Federal Government are "few and defined", while those of the States are "numerous and indefinite."
emphasis on the bold being mine