That could be a toss-up, though at least we can agree that conservatives in good faith can disagree on this, right?
On this issue, I think conservatives can disagree on the decision of the federal government to regulate the interstate commerce of drugs. That is, some would say it is not the business of the federal government and that each state should decide.
But I am surprised that conservatives would disagree on the fact that the federal government has the power to do so.