After 70 years of Prohibition, I'm a little cynical on that point. When did we ever ask for these laws, or grant politicians the authority to pass them? The best would be a Roe V. Wade-type constitutional declaration, based on the state reservation of power, the 18th/21st Amendments (these powers are not in the Constitution, so an Amendment was not necessary), the 4th Amendment (officer suspicions≠probable cause) or some other argument which deprives the government of the power to legislate substance possession. We'll have to wait for that, but I'm optimistic that Obama will indeed seat such Justices as the opportunity arises.