As another poster has already quipped, there's practically zero chance of that happening without overhauling the entire government. It may be hard for us, makers and engineers, to see why anyone would obstinately refuse to accept facts as ever more data flows in, but that's not how real life works. Sadly.
Politics and engineering are, in certain aspects, polar opposites. In politics changing one's opinion, even in face of facts, is a mark of incompetence. That's a big factor in why it takes so long to reverse bad decisions. While enough (read: too many) of the representatives who voted 'yay' are still in office, they will keep attacking any attempts to undo whatever they have done or approved. And because the big decision was to make all drugs illegal, there will be constant squeeze to push all other decisions further in that direction.
Reversing the earlier error is simply inconceivable. It takes a new generation of elected representatives to revoke old laws.