Congress realized it did not have the authority under the Constitution to outlaw alcohol, so it passed a Constitutional Amendment (18th), and later recended it with the passage of the 21st Amendment. That being the case, then where is the Constitutional Amendment allowing the Federal Government to make it illegal to have drugs? Hint: There isn’t one!
So how did Congress achieve this feat? Simply, they bastardized the “Commerce Clause”. The exact same clause that’s been there from the beginning, the just gave it new meaning.
You nailed it!