Paul Krassner may well be right that marijuana prohibition is a bad idea (though I'm not an expert on the subject, and thus don't have an informed opinion on this).
But why blame the Supreme Court for this, on the grounds that its "decision on medical marijuana was incredibly inhumane" -- or for that matter, as Mr. Krassner suggests, that the war on marijuana more broadly is inhumane and foolish? Congress banned marijuana, with no medical exemption. Congress has failed to amend the ban. Both Democratic and Republican Presidents have enforced the ban. They are the ones who could have (and perhaps should have) modified, repealed, or declined to enforce the law on "humaneness" grounds.
The Supreme Court, in its decision this morning, didn't have the right to judge the law's humaneness. The question facing the Supreme Court was whether Congress's power to regulate interstate commerce, and to do what was necessary and proper to implement such regulations; the majority said yes, the dissenters thought no, but neither one was entitled to make the decision based on what's humane and what's not. There is no Humaneness Clause in the Constitution that requires all government actions to be humane; the Clauses at issue today were the Commerce Clause and the Necessary and Proper Clause.
The Court was indeed asked to decide whether the law violated the "substantive due process" doctrine, but was procedurally unable to reach that; and in any event, for all its merits or flaws, that doctrine doesn't empower judges to strike down any law that is inhumane. And a few years ago, the Court did reject the argument that people could raise a "medical necessity defense" to prosecution for marijuana distribution, but rightly -- and unanimously -- decided that it was up to Congress to decide whether to recognize such a defense. The Justices' job was to follow the law, not to override Congress's judgment about what's medically necessary.
If the prohibition of marijuana, or of medical marijuana specifically, is unsound and inhumane, blame your elected representatives. Don't blame the Justices, whose job is to decide whether the prohibition is unconstitutional, not whether it's inhumane. (Or, if you prefer, ask your elected representatives to enact a constitutional amendment that does add a Humaneness Clause to the Constitution -- but then be prepared for the Justices to use it in ways that you might not much like, especially if you're a liberal, the Justices are mostly conservative, and their views of humaneness aren't the same as yours.)
UPDATE: Turned on comments, as an experiment -- I'd love to see people's thoughts on this (though I'm afraid I can't promise to respond to them). Please keep things substantive, polite, and on-topic.
FURTHER UPDATE: I deleted two comments that struck me as rather on the rude side. Naturally, many other posters on this blog may have a very different view about what posters should do about comments; and of course bloggers on other blogs have a wide range of approaches towards managing comments. But my view (which is supported by the software that the Huffington Post organizers have provided us) is that the author of a post is something of an editor of a comments thread, and that this editing process creates extra value -- and that rude, off-topic, or unsubstantive comments lower the value of the thread, rather than raising it. (For more on this general issue, see Part I of this article.) Naturally, people are entirely free to post whatever they please elsewhere. I just thought that I'd note that this is the way I prefer to edit the little corner of the blogosphere over which people have been kind enough to give me editing authority.