Subsidiarity and Medical Marijuana

I tend to read the Constitution in a way that takes seriously the idea of enumerated -- and therefore limited -- powers.  Accordingly, I tend to frame "federalism" cases in terms of the presence (or absence) of constitutional authorization for the federal action in question, and less in terms of "states' rights."  (It is fascinating, for me, to see the Court's two leading "originalists" -- Justice Scalia and Thomas -- dividing on this case.  If nothing else, the case is a welcome reminder to journalists, law students, and scholars that the Court, the Justices, and constitutional philosophy are more complicated than "activist" and "strict constructionist", or "living Constitution" v. "traditionalist.").  So -- responding briefly to Rob's post -- the constitutional question for me is (primarily), "Does Congress have the power to criminalize possession and use of marijuana, grown in-state, even for medicinal purposes?"  (And, if the answer is yes, is there anything that requires Congress to exempt the conduct at issue here?)  This is (for me) a difficult question. 

Turning to the matter of Catholic Social Thought, though, it strikes me that "subsidiarity" cuts both ways.  (I'm playing the Devil's Advocate here, because I think my preferences and intuitions line up with Rob here).  If one believes that the regulation of certain drugs is a wise public policy, then one could certainly conclude -- invoking subsidiarity -- that a national strategy (one that is intolerant of state-by-state opt-outs) is essential to the policy's success.  (It is hard -- or harder -- for the national government to pursue its policy if it has to negotiate state-by-state opt-outs of various kinds).  Or, if one is agnostic or doubtful about the wisdom of a national drug policy, one could then invoke subsidiarity to defend a particular state's normative determination, or experiment.

Rick   

UPDATE:  Marty Lederman and Tom Goldstein, over at SCOTUSBlog, have assembled an all-star team of scholars and commentators to discuss today's medical-marijuana decision.  And, Larry Solum has a very detailed analysis, here.