The Justice Department on Thursday said it would not sue to block laws legalizing marijuana in 20 states and the District of Columbia, a move that proponents hailed as an important step toward ending the prohibition of the drug.  http://www.nytimes.com/2013/08/30/us/politics/us-says-it-wont-sue-to-undo-state-marijuana-laws.html?ref=us    Marijuana advocates praised the decision as a potentially historic shift in the federal government’s attitude […]