While I'm all for the provision, and my representative will have to get yet another letter expressing my disapproval, I find it a little ironic that our legislative branch must go about trying to undo what it allowed to happen in the first place by placing provisos on the pursestrings. The Controlled Substances Act grants sweeping powers to the executive branch, yet we don't see any proposals to actually reform it (or better yet, scrap it) when it is clear the bureaucracy is incapable of using rational studies to schedule drugs. Rather than question the wisdom behind the CSA, it is more efficacious to leave the behemoth untouched and simply tell the DEA they must not use the power that was authorized to them.
On a lighter note, this might help explain why the votes for this amendment still keep coming up short:
YouTube - Incarcerex: It's Time for a New Bottom Line