The States granted the national government the power to regulate commerce "among the several states", not the power to regulate anything that they can imagine might affect interstate commerce.
The "substantial effects" doctrine is a New Deal invention, not an application of an enumerated power as intended by the people who wrote and ratified the Constitution. It's become the primay means of expanding federal government power far beyond what was intended and authorized by the Constitution.
Ron Paul and Clarence Thomas get this right.
Exactly.