Supreme Court Justice Antonin Scalia said Sunday the Second Amendment leaves open the possibility of gun-control legislation, adding to what has become a slow-boiling debate on the issue since the Colorado movie theater massacre earlier this month.

Scalia, one of the high court’s most conservative justices, said on “Fox News Sunday” that the majority opinion in the landmark 2008 case of District of Columbia v. Heller stated the extent of gun ownership “will have to be decided in future cases.”

“We’ll see,” he said.

Scalia’s comments follow the July 20 massacre at the Aurora, Colo., movie theater in which the alleged gunman, with the help of a semi-automatic weapon and an ammunition clip that could hold as many as 100 rounds, killed 12 and wounded 59 others.

His comments also follow those of lawmakers who have called for tougher gun-related laws in the wake of the shootings – most recently New Jersey Sen. Frank Lautenberg and New York Rep. Carolyn McCarthy, Democrats who said Sunday they will introduce legislation this week to “make it harder for criminals to anonymously stockpile ammunition through the Internet, as was done before the recent tragic shooting in Aurora, Colorado.”

They are scheduled to announce the bill to the public Monday outside City Hall in New York City.

New York City Mayor Michael Bloomberg, a Republican turned independent, has been among the most vocal on the issue since the mass shooting.

On Friday, Bloomberg in an editorial for his Bloomberg News, suggested the problem in Washington is that lawmakers do not want to vote for tougher gun laws out of fear of retribution from the powerful National Rifle Association.

The editorial was titled “How to Break NRA’s Grip on Politics” and suggested the political impact of the group might be exaggerated.

“In Congress, the NRA threatens lawmakers who fail to do its ideological bidding, although its record in defeating candidates is much more myth than reality,” the editorial stated.

Just hours after the shooting, Bloomberg, co-founder of Mayors Against Illegal Guns, called on President Obama and Mitt Romney to address the issue from the campaign trail.

“Soothing words are nice, but maybe it’s time that the two people who want to be president of the United States stand up and tell us what they are going to do about (gun violence) because this is obviously a problem across the country,” Bloomberg said.

Then late last week he suggests police officers go on strike until additional laws are passed. He backed off that statement but has continued to press the presidential candidates and others in Washington to make changes.

Congress passed a 10-year ban on assault-style weapons that expired in 2004, but there has since been no real interest among Capitol Hill lawmakers to reinstitute a ban.

On Wednesday, Obama talked about possible changes, but the following day Senate Majority Leader Harry Reid said he couldn’t fit the gun control debate into the schedule.

Asked if the Senate might debate the issue next year, Reid said, "Nice try."

The president was not specific about what measures he'd like to see enacted when he touched on the issue in a speech to the National Urban League. He affirmed his belief in Americans' right to own guns, but he singled out assault rifles as better suited for the battlefield.

"I believe the Second Amendment guarantees an individual the right to bear arms," he said. "But I also believe that a lot of gun owners would agree that AK-47s belong in the hands of soldiers, not on the streets of our cities."

Obama also called for stepped-up background checks for people who want to purchase guns and said he would also seek a national consensus on combating violence.

White House Press Secretary Jay Carney clarified Thursday that the president is not necessarily talking about new laws.

Scalia said exceptions to gun rights were recognized when the Second Amendment was written, including a tort that prohibited people from carrying a “really horrible weapon just to scare people like a head ax or something.”

Republicans have largely said new laws are not the answer. Romney, pressed on the gun control issue in an NBC News interview during his visit in London, said changing laws won't "make all bad things go away."

"I don't happen to believe that America needs new gun laws,” he said.

Romney said a lot of what alleged shooter James Holmes did was clearly against the law.

“But the fact that it was against the law did not prevent it from happening," he said.

According to a Gallup poll in 1990, 78 percent of those surveyed said laws covering the sale of firearms should be stricter, while 19 percent said they should remain the same or be loosened.

By the fall of 2004 support for tougher laws had dropped to 54 percent. In last year's sounding, 43 percent said they should be stricter, and 55 percent said they should stay the same or be made more lenient.

Scalia, in his wide-ranging interview with Fox News also repeated his criticism of Chief Justice John Roberts and the majority opinion this summer that largely upheld President Obama’s Affordable Care Act, particularly the part that called the consequence for non-compliance a tax, not a penalty.

"You don't interpret a penalty to be a pig,” he said. “It can't be a pig. … There is no way to regard this penalty as a tax."

The Associated Press contributed to this report.