Jacob Sullum corrects some dubious arguments against Prop 19. On its constitutionality:
Nine former heads of the Drug Enforcement Administration claim the initiative conflicts with the federal Controlled Substances Act and therefore violates the Supremacy Clause, which says "this Constitution, and the laws of the United States which shall be made in pursuance thereof...shall be the supreme law of the land." The Supreme Court has upheld national marijuana prohibition, even as applied to purely intrastate cultivation and possession of the drug, through an absurdly broad reading of the federal government's authority to "regulate commerce…among the several states." But it has never held that the Constitution requires states to impose their own penalties for crimes created by Congress.
Assuming Californians approve Prop. 19, which is ahead by 11 percentage points in the latest poll by the Public Policy Institute of California, the feds will not have the resources to enforce marijuana prohibition throughout the state on their own. That's a good thing, since the freedom to experiment with different policies is one of federalism's main virtues.