Here's a link to the Register's editorial on San Diego County's decision to continue its court case against California's medical marijuana law all the way to the U.S. Syupreme Court, after being denied in district court, in the California appellate court, and having review denied by the California Supreme Court. It's hard to imagine the county, which doesn't want to implement the legislation requiring counties to do the screening for a voluntary ID card for patrients, will meet with better success there. There's no conflict among federal circuits for the high court to resolve and so little compelling reason to take the case.
I was in the Supreme Court chambers when the court heard the original medical marijuana case, the request by the Oakland Cannabis Buyers Club to have a "necessity" defense recognized for certain medical marijuana users under federal law. The court denied that, but during the course of oral argument Justice Ginsberg asked the government attorney why the government wasn't invoking the "supremacy clause" to invalidate California's medical marijuana law. The government attorney replied that this was simply one of those instances where, given the federalist nature of our constitutional structure, some states would simply have different laws regarding the medical use of cannabis than federal law, and it would be up to federal agents to enforce federal law and state agents to enforce state law. That was a welcome recognition of federalism by the Bush Justice Dept., which hardly did so consistently. The likelihood that the government would try to invoke the supremeacy clause now, after all these years, seems low.