With the District of Columbia now asking the Supreme Court to uphold its strict 30-year handgun ban, gun-rights and gun-control advocates are headed for a potential showdown. In March, a panel of judges for the U.S. Court of Appeals for the D.C. Circuit ruled the city’s prohibition unconstitutional. In May, the full appeals court declined to reconsider the ruling. Now if the high court decides to hear the case, legal experts expect an historic test of the Second Amendment with wide-reaching ramifications.