Professor Rosenthal filed a friend-of-the-court brief in the United States Supreme Court on behalf of the U.S. Conference of Mayors in McDonald v. City of Chicago, a case in which the Court will decide whether the Second Amendment’s right to keep and bear arms applies to state and local governments. The brief argues that the Second Amendment’s eighteenth-century conception of the right to keep and bear arms has given way over the course of American history to a broader conception of state and local police powers to impose reasonable firearms regulation, and for that reason the Second Amendment should not be incorporated into the Fourteenth Amendment’s limitations on state and local powers.