Obama supports a ban on military-style assault weapons and a requirement that purchasers at gun shows undergo background checks. The president will also look at efforts to restrict high-capacity magazines that can accept more than 10 rounds of ammunition, according to White House press secretary Jay Carney.
The Heller decision resolved a constitutional question that had lurked for two centuries: whether the Second Amendment protects individuals even though it refers to state-run militias. The ruling, which divided the court 5-4 along ideological lines, struck down the District of Columbia's handgun ban.
Buried within the 21,000-word majority opinion was a paragraph that gave gun-control advocates reason for hope. Gun rights are "not unlimited," 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," he said. Nor was the court questioning "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."
Scalia also said the Second Amendment protects weapons that are in "common use" and not those that are "dangerous and unusual."
Gun-rights advocates say the Heller ruling established important limits. The court's backing of weapons in "common use" would doom a law that limited magazines to 10 rounds, says David Kopel, a policy analyst at the Washington-based Cato Institute and adjunct professor of constitutional law at the University of Denver.
"It's extremely common these days for regular guns bought by regular people to have ammunition magazines in the 11-to-19 range," Kopel said. "I think the ban at 10 is plainly unconstitutional under that."
Similarly, Congress wouldn't be able to ban the weapon that police say Lanza used, the Bushmaster AR-15 assault rifle, said Gene Hoffman, chairman of the Calguns Foundation in San Carlos, Calif.