I trust that Leahy will go beyond the question of marijuana consumption to address production and distribution, which are the real issues as far as federal meddling goes. UCLA drug policy expert Mark Kleiman, who has advised the Washington State Liquor Control Board on marijuana regulation, argues that the administration also should go beyond "guidance about enforcement" by formalizing an agreement that the feds will refrain from interfering in exchange for state help with controlling interstate smuggling of newly legal marijuana. (Stuart Taylor made a similar proposal in a Brookings Institution paper published last April.)

In a new Journal of Drug Policy Analysis article, Kleiman notes that the Controlled Substances Act says the attorney general "shall cooperate with local, State, and Federal agencies concerning traffic in controlled substances and in suppressing the abuse of controlled substances." Toward that end, "he is authorized to…notwithstanding any other provision of law, enter into contractual agreements with State and local law enforcement agencies to provide for cooperative enforcement and regulatory activities." Such a contract, Kleiman says, would provide more assurance of federal forbearance than simple inaction. Alternatively, he says, Congress could authorize the attorney general to issue "waivers" exempting state-legal marijuana producers and sellers from federal prosecution as long as certain conditions aimed at minimizing diversion are met.

Here is Kleiman's response to those who argue that the Justice Department has a duty to vigorously enforce marijuana prohibition even in states that have opted out:

To the immediate objection that the Executive Branch—charged by the Constitution with the "faithful execution" of the laws—has no authority to acquiescein the violation of some of those laws, there is an equally immediate rejoinder; those laws are now being violated and will continue to be violated, in ways the Executive is practically powerless to prevent in any case and still more powerless without the active engagement of state and local enforcement agencies. If "the abuse of controlled substances" can be more effectively suppressed with cooperative agreements than without them, then the mandate to cooperate for the purposes of the Act might be best carried out by explicitly agreeing not to do what the federal government cannot in fact do with or without such an agreement.