It's called "tyranny of the majority". The Constitution was designed to prevent it from happenning. That is why the federal government is given certain powers. All powers not given to federal government belong to the states and the people.
Amendment X - The powers not delegated to the United States by the Constitution, nor prohibited by it to the states, are reserved to the states respectively, or to the people.The states are supposed to decide for themselves on most issues. Under which power can the feds legally claim a right to forbid the growing and selling of drugs within a state?
Well like others here have said, an amendment had to be passed to enact prohibition. And pot is a plant ferchrissake. At most, for interstate commerce purposes, the stuff could maybe be regulated when transported across state lines, strictly for control of agricultural disease.
But good luck now getting the FedGov to act within it's enumerated powers.
Dave in Eugene