Antonin Scalia's 2008 Ruling Set Parameters for Today's Gun Control Reform Debate

The horrific mass shooting at a gay nightclub in Orlando, Florida, that left 49 dead. The Senate debate on efforts to prohibit those on the terrorist and no-fly watch lists from buying firearms. Monday's ruling by the Supreme Court not to take up a case banning assault weapons. All of these gun stories that have been dominating the news over the past weeks have one man at the center: the late Supreme Court Justice Antonin Scalia.

When he died unexpectedly this winter, the 79-year-old Ronald Reagan appointee was a hero among conservatives, known primarily for his blistering dissents when the court veered to the left. But he was also famous, and infamous, for his opinion on gun control. In 2008, Scalia wrote a landmark opinion for the majority of the court that upheld an individual's right to bear arms. His ruling infuriated liberals and settled the questions, at least for now, about whether the phrase "well regulated militia" in the Second Amendment means people have a right to a gun only if they are part of such a group or whether they have a right on their own to buy and own a gun. Scalia's ruling said that it is an individual right.

The case had been brought by a District of Columbia courthouse guard who wanted to buy and maintain a gun at home, despite D.C.'s sweeping handgun ban. Scalia ruled that the Constitution entitled the man, Dick Heller, to own a gun and use it at home for self-protection. For good measure, Scalia not only knocked down the city's handgun ban but also declared that its requirement that guns be kept disassembled or with trigger locks was unconstitutional. No, Scalia ruled, the founders meant for guns to be available for self-defense, and trigger locks would make it too hard to take on an intruder.

The District of Columbia v. Heller ruling still looms large today because it left open a lot of questions that are now at issue. Consider semi-automatic weapons like the AR-15 rifle, which has been used in a number of high-profile shootings, including the deadly massacre at Sandy Hook Elementary School in Newtown, Connecticut, in 2012. Are bans on this kind of weapon allowed under Heller?

On Monday, the Supreme Court let Connecticut's ban on such weapons remain. It did the same in December after an effort to overturn a similar ban in Highland Park, Illinois. That doesn't mean the court is embracing these bans, only that it's put off ruling on them to another day. If the court takes them up, and at some point it surely will, its decision will come back to Scalia's famous opinion in the Heller case.

And how the justices would rule on the constitutionality of owning an AR-15 is up in the air. Despite his deserved conservative reputation, Scalia left some gifts for liberals in his Heller ruling. He wrote that the right to bear arms had limits. "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."

The late justice also more generally offered the belief that "like most rights, the right secured by the Second Amendment is not unlimited." It is "not a right to keep and carry any weapon whatsoever in any manner whatsoever and for whatever purpose." For instance, Scalia said concealment laws were permitted at the time of the Constitution's ratification and should be permitted today.

The issue that Scalia left future courts to grapple with is what constitutes a protected weapon. He wrote that the Constitution protects weapons that could be carried and were in common use. What he didn't say in the opinion—and what the court has deferred ruling on—is whether an AR-15 fits the bill for a common weapon. On one hand, it's certainly not rare. There are more than a million in circulation. On the other hand, it's not as ubiquitous as ordinary rifles and handguns. At some point, the John Roberts court will wrestle with the questions Scalia left unanswered, or the justices will leave it to the political process.

When the Senate on Monday night takes up the issue of curtailing the sale of guns to those on various government watch lists, Scalia's opinions will also loom large. Would the Heller opinion allow such tightening? In all likelihood, the restrictions could survive some kind of court challenge under Heller, which permits restrictions on gun sales in the interest of public safety. If there is to be a court challenge to such restrictions, they're much more likely to be about due process—whether those who claim to be unfairly on the watch list have been given an adequate right to appeal their denial of sale. Chances are that they'd lose, given the national priority placed on preventing terrorism. After all, Heller was an appealing plaintiff—a law enforcement officer who knew how to responsibly use a weapon and was assigned one as part of his job. A plaintiff in a watch list case would have a much harder sell.

If you needed another reminder of how important the Heller case was and is, look at Monday's proceeding in a Connecticut courthouse, where gun manufacturers and sellers face a case saying that they are liable for mass shootings involving their high-powered weapons. The defendants are arguing that Congress gave them liability protection and that the case should be dismissed. Had Scalia been in the minority in Heller, it would have been much easier to take on high-powered weapons without having to turn the case into one involving liability.

Scalia's Heller opinion, and the dissents offered by his liberal colleagues, makes for fascinating reading. They trace the history of arms during the Revolutionary War period, and even delve into grammar and comma placement to try to understand what the Founding Fathers meant in the Second Amendment. Throughout much of American history, the anti-Scalia view held sway, but the associate justice built on years of cases and political lobbying to define gun ownership as a sacred individual right.

What he didn't do was define every last case of what constitutes a gun and where a gun's use can be regulated. And that's something the United States will continue to do after every tragic shooting, like the one in Orlando.