Excellent (and very in depth) analysis from Prof. Lawrence Solum at Legal Theory Blog.
The analysis link takes you to the header post, which links to the detailed sections. Lots of information in there.
In addition, I'd like to comment on Prof. David Bernstein's post here on Volokh...this is part of what Bernstein had to say: "The five-member majority of the Court simply does not take federalism seriously." He goes on to say, "It seems we do to some extent live under a system where the personal preferences of the Justices, having nothing to do with the history, text, or logic of the Constitution, dictate when the Supreme Court will or will not intervene to overturn particular regulations."
This is a typical conservative ideology - if you don't agree with a decision, BLAME ACTIVIST JUDGES!!! It is also lazy. It is readily apparent that those advocating that the federal governement has no say in national drug enforcement policy do not seem to take the Commerce Clause seriously. The Court established long ago in Wickard that this type of legislation, which controls activity that has a substantial economic effect on commerce, falls within the Commerce Clause, and that the federal government has the right (if not the obligation) to appropriately legislate those areas. The Constitution embraces federal government control over key national issues...this is the very purpose of the Commerce Clause.
Prof. Bernstein is of the extreme conservative/libertarian mold - he has argued in the past that the Court's rejection of the freedom of contract, and repudiation of Lochner, was actually a set back for minorities and women - because it allowed 'special preference' laws - for example, minimum wages, a maximum hour work week, and notably minimum wages for women during WWII. In fact, Bernstein is among the forefront of advocating the currently popular re-introduction of Lochner into Constitutional law. What Bernstein, and other libertarians of similar distinguished credentials, fail to appreciate, is that these 'special preference' laws are designed for the benefit and protection of these classes - be it blue collar working classes, or minorities and women. The federal government has a role in ensuring the due process and equal rights of its citizenry - a return to Lochner is an abdication of that Constitutional responsibility.
Whatever your opinions about the use of medical marijuana specifically, or legalization of drugs generally, this is a federalism question - and anyone making the argument that the federal government does not have a role in drug enforcement generally is simply catering to their own personal preferences. Not necessarily the preference to legalize drugs, but their preference of a dead Constitution...or crusading to return the Constitution-in-Exile...