Michael Barone writes that, in light of the Justice Department’s recently announced intent to allow federal prosecutions for marijuana possession, supporters of the industry are frustrated by a lack of votes in Congress to change the law. Barone suggests that the Twenty-first Amendment provides a way for federalism to resolve this conflict. The second section of that amendment, which permits states to prohibit alcohol if they choose to do so, allows for differing federal and state positions on the issue. Read more here.