The marijuana trade affects interstate commerce, just like the health insurance trade. That’s why Congress has the power to regulate both. If someone grows pot in their home for their own use, how does the Commerce Clause come into play, other than by the insanity followed in Wickard?
Scalia: ...the authority to enact laws necessary and proper for the regulation of interstate commerce is not limited to laws governing intrastate activities that substantially affect interstate commerce. Where necessary to make a regulation of interstate commerce effective, Congress may regulate even those intrastate activities that do not themselves substantially affect interstate commerce. --J. Scalia, concurring in Gonzales v Raich That's how. Again, I don't agree with that, it's simply what they had to do to keep their laws in place. And what they will do time and time again when they want to keep their laws in place.