The power to regulate commerce is not the power for the government to regulate whatever it wants.
But that’s how they use it today.
How did this happen?
They changed the definition of the word commerce.
In the founding era, commerce basically meant trade. As Rob Natelson noted in his paper “The legal meaning of commerce in the Commerce Clause,” this included “buying and selling products made by others (and sometimes land), associated finance and financial instruments, navigation and other carriage, and intercourse across jurisdictional lines.” [emphasis added]
In simple terms, the interstate commerce clause empowers the federal government to regulate the movement of goods across state lines, along with a few ancillary activities.
But today, the feds define commerce as any “economic activity.” With this expansive definition, they use the commerce clause to regulate plants grown in your own backyard for your own use, and pretty much everything else imaginable. As Clarence Thomas put it in his dissent in Gonzales v. Raich (marijuana case), with this definition of commerce, the federal government has “no meaningful limits.”
Why did the people who drafted the Constitution include the power to regulate interstate commerce to begin with?
James Madison told us that “It is very certain the power to regulate interstate commerce grew out of an abuse of the power of the importing states in taxing the non-importing.”
In other words, the power was intended to promote free trade.
In practice, states were trying to tax each other’s products. The commerce clause was included to allow the federal government to stop this. It was never intended to give the federal government power to regulate manufacturing, agriculture, labor laws, workplace safety, or the host of other activities the feds now micromanage under the banner of “regulating commerce.”
As Madison put it, it was “ a negative and preventative provision against injustice amongst the states themselves, rather than as a power to be used for the positive purposes of the General Government.”
But as they always seem to do — the federal government took this relatively limited power and ran with it.