Why not leave this to the states to decide?
> States will control the possession, production, or distribution of cannabis, the draft says, while shipping marijuana into states that have not legalized it will be prohibited.
As opposed to the status quo where in principle the federal government could decide to prosecute... shall we say "marijuana market participants"? in states where it is legal.
One somewhat related item -- the federal prohibition of alcohol (Amendment 18) and its repeal (Amendment 21) -- stems from the commerce clause, which enumerates the powers held by the Federal legislative branch: including the regulation of intrastate and interstate commerce. IANAL or a constitutional scholar, so grains of salt.
Fun fact: though the 21st amendment came into being in 1933, Mississippi was one of the last states to repeal a state-wide dry law in 1966. [0]