In the wake of the shooting in Newton, Connecticut that left 27 dead before the gunman took his own life, President Obama has pledged to submit broad, new gun control proposals to Congress by January, and will work to overcome the political opposition posed by advocates of gun rights.  But a major factor in the potential passage of new gun control laws is the Supreme Court’s decision in 2008 in District of Columbia v. Heller, which advocates for both gun control and gun rights claim is written in their favor.

In Heller, a 5-4 majority, led by Justice Antonin Scalia, held that the Second Amendment protects an individual right to possess a gun unconnected with service in a militia, and to use the gun for traditionally lawful purposes, such as in the home for self-defense.  That decision largely overturned the District of Columbia’s handgun ban—at the time considered the strictest in the nation—and appeared to limit the possibilities for instituting stricter gun control laws, especially under a conservative Supreme Court.

However, that same decision also recognized a variety of restrictions that could be legally imposed.  As Justice Scalia wrote, “nothing in our opinion should be taken to cast doubt on longstanding prohibitions on the possession of firearms by felons and the mentally ill, or laws forbidding the carrying of firearms in sensitive places such as schools and government buildings, or laws imposing conditions and qualifications on the commercial sale of arms.”  In addition, Heller upheld the Court’s ruling in United States v. Miller, which limited the type of weapon to which the Second Amendment applies—i.e., those in common use for lawful purposes.  Under that precedent, a ban on sawed-off shotguns or machine guns would still be legal.

The federal assault weapons ban, which was enacted in 1994 but expired in 2004, banned both assault guns and guns with high-capacity magazines holding more than 10 rounds of ammunition.  Senator Dianne Feinstein (D-CA), the sponsor of the 1994 law, said that her latest proposal would again ban both.

Unsurprisingly, legal advocates on both sides of the proposal have already disagreed about the applicability of the Heller decision to the new gun control proposals.  David Kopel, research director of the Independence Institute, says that many handguns and rifles, which are “overwhelmingly” possessed by law-abiding citizens for lawful purposes—thus passing the Heller test—contain magazine rounds that exceed, in some cases, 35 rounds.  However, others, such as Adam Winkler, a law professor at UCLA and former Supreme Court Justice John Paul Stevens, have suggested that Heller would not interfere with the majority of gun control proposals, including better background checks, enhanced mental health reporting and a ban on high-capacity ammunition clips.  Given this disagreement, which can already also be seen between federals appeals courts in New York, Virginia, and Illinois, it is likely that Heller will continue to play an important role in shaping any new gun control laws that Congress may pass.