OK, I skimmed a lot of the 750 replies so sorry if someone else brought this up, but to me the most important part of this decision was a footnote. Stevens all but said that if the studies cited by the NORML crowd are correct, then, as a matter of law, marijuana could not be considered a Schedule I drug (the "hardest," most closely regulated drugs, which have no redeeming quality and cannot be possessed at all).
According to the opinion, NORML has brought five lawsuits trying to get the federal government's Schedule I classification of marijuana overturned. All failed. Justice Stevens seems to be inviting them to try a sixth time, and is hinting at the blueprint for success, at least in his opinion (and, presumably, the opinion of the other justices who signed the opinion). In other words, he protected the precious Commerce Clause big government types love so much, while laying the framework for court-imposed nationwide legalization similar to California's in a few years.
This is new, welcome! You will find a great multitude of opinions here...
So that may well be -- Souter's foot, that is. Yet the worse if so for Liberty.