If Congress opens a serious debate on new federal restrictions on firearms in the wake of the Newtown school shootings, the U.S. Supreme Court’s landmark Second Amendment decision will be fodder for proponents and opponents.

Not surprisingly, both sides in the gun control debate, at loggerheads for decades, disagree on how much room the 2008 District of Columbia v. Heller decision offers for new regulations, particularly of the assault-type rifle used to kill 20 children and six adults on December 14.