The U.S. Supreme Court handed gun-rights advocates major ammunition when it interpreted the Second Amendment four years ago.

The landmark 2008 case, District of Columbia v. Heller, expanded the right to bear arms beyond the long-held view that it was centered on maintaining a “regulated militia.”

Instead, the court by a 5-4 decision found the amendment protects an individual’s right to possess a firearm for traditional lawful purposes. It struck down the District of Columbia’s handgun ban, then the country’s strictest.

“With one vote, the court changed 70 years of understanding of what was the Second Amendment, changing it from a collective right to an individual one,” said Howard Simon, executive director of the American Civil Liberties Union of Florida.

Now that calls for tougher gun laws are at a fever pitch in the wake of the horrific Connecticut school shootings, the Heller decision is a ping-pong ball for both sides.

The shooting left 20 first-graders and six educators dead at the hand of a disturbed young man. Those who hold the Second Amendment dear to their hearts have donned the Heller decision as armor against criticism that America’s gun laws are far too lax, while those looking to amend the nation’s guns laws are mining its nuances.

The 4.3 million-member National Rifle Association broke its silence on the shooting at a news conference Friday. NRA president Wayne LaPierre called for armed police officers to be posted in every American school and criticized the media and video game makers for promoting violence in society.

Untested

One thing the two sides seem to agree on is the Supreme Court opinion leaves a lot of room for interpretation. Litigation on the issue already was percolating in the lower courts before the mass killing in Connecticut.

Justice Antonin Scalia, who wrote the majority opinion, said the Constitution holds the right to bear arms for “lawful purpose of self-defense.” But he also said states can prohibit carrying “dangerous and unusual weapons” and restrict the right to bear arms by felons and the mentally ill.

He also expected the issue to return to determine what weapons qualify as dangerous.

“The Supreme Court just kicked the can down the road,” Simon said. “Heller was just a statement on conservative jurisprudential philosophy.”

Michael R. Masinter, professor at Nova Southeastern University’s Shepard Broad Law Center in Davie, said Heller failed to establishes a standard of review to test the constitutionality of gun restrictions.

“I think Congress should do what it thinks is appropriate, and if the Supreme Court wants to find it overreached, then so be it,” Masinter said.

The horror in Connecticut came after the shooting deaths of 12 moviegoers at a Denver-area movie theater in July and the January 2011 rampage in Tucson, Arizona, that left six dead and critically wounded Congresswoman Gabrielle Giffords.

All three shooters were in their early 20s, often the age for the onset of schizophrenia. Adam Lanza, the Connecticut killer who took his own life, reportedly snapped because his mother was working to get him institutionalized.

U.S. Senator Diane Feinstein, D-California, has called for a renewed assault weapons ban, which expired in 2004. President Barack Obama has said he supports background checks for gun buyers at gun shows and restriction on high-capacity magazines.

Australia found success in stricter gun laws that included a buyback of more than 650,000 guns after a rampage in 1996 left 35 dead. There hasn’t been a mass shooting in that country since.

Gun culture

David Kopel, a policy analyst at the Washington-based Cato Institute and adjunct professor of constitutional law at the University of Denver, said the practicality of duplicating Australia’s efforts in the U.S. would run smack into Heller.

He said Feinstein’s proposals would have “serious problems” because about three-quarters of all handguns sold in the U.S. are semi-automatics that hold 11 to 19 rounds.

Gene Hoffman, chairman of the San Carlos, California-based gun rights organization Calguns Foundation, noted a buyback program for semi-automatic weapons would target 60 percent of the guns in the U.S.

Hoffman said the AR-15 rifle used by Lanza is one of the most popular firearms in the country and can be used in hunting coyotes or protecting oneself from mountain lions, which wander into suburban areas in his area.

Attorney Lida Rodriguez-Taseff, a partner at Duane Morris in Miami, has worked in South Florida to stem gun violence. She doesn’t read Heller as preventing the government from doing a weapons buyback.

“The question is whether people will consider it a good policy,” she said.

Rodriguez-Taseff insisted the government should be able to drastically limit ammunition clips.

“Under Heller, it could be asked: What is the lawful purpose for needing this much ammunition?” she said.

Hoffman said proposals like Feinstein’s are akin to legislating by lightning strike.

“It’s problematic,” he said. “We have been forming a consensus that Heller might mean we can have a rational conversation, but one insane individual means that conversation has gone to a place in which the most popular rifle could be banned.”

He favors more thorough background checks and databases to keep guns out of the hands of mentally ill people. He said the system in California, which takes away guns rights of anyone committed for three days or more, could be adopted.

But Simon comes back to a question many ask: “Just because I have a constitutional right to own a weapon to provide for my safety, does that mean I can own semi-automatic weapons, a bazooka, even have a tank in my backyard?”

He said the Heller decision gives no real direction.

“All Heller did was leave it for further litigation to determine permissible regulation,” Simon said.