Ten years ago, when a divided Supreme Court ruled in District of Columbia v. Heller that the Second Amendment includes a right to individual possession of firearms, dissenting Justice John Paul Stevens lamented that it was “a law-changing decision” that would cause “a major upheaval.”

Heller is a landmark case in many ways, not least of which for Justice Antonin Scalia’s majority opinion, one of his most discussed and most quoted. But a close look at decisions over the past decade indicates that the case has not revolutionized judicial treatment of gun laws in quite the way that Stevens and others might have feared or gun rights supporters might have hoped.

Some gun rights advocates have suggested that’s because lower courts have been thumbing their nose at Scalia’s opinion in an act of massive resistance akin to the South’s refusal to desegregate after Brown v. Board of Education.

But Scalia’s opinion made clear that the decision would leave untouched many “longstanding prohibitions” on the use of guns. In practice, courts have concluded that these prohibitions and others like them pass constitutional muster. Our research confirms, as other research has suggested, that most Second Amendment claims fail. We also find that most fail precisely because of limitations that Heller itself places on the right to bear arms.

This finding has new relevance as Americans debate yet another school shooting, this time in Santa Fe, Texas. Many politicians, advocates, and commentators have suggested that the Second Amendment prohibits further gun regulation. But hundreds of judicial decisions from across the country indicate otherwise.

The Second Amendment, as courts have come to interpret it, undoubtedly protects a fundamental constitutional right, but it also leaves room for a potentially wide range of regulation.

The decision remains a big deal, but it didn’t overturn the entire gun-control regime

Justice Stevens was right to call Heller a “law-changing decision,” and it has undoubtedly had an impact on some types of gun regulation, for example by limiting some highly restrictive public carry regulations, including public carry bans. The Court’s decision might also have had a deterrent effect on gun regulation, as it gives a powerful rhetorical tool to those seeking to prevent or roll back gun laws through the political process.

But as a matter of law, gun jurisprudence has not been turned upside down, as Justice Stevens feared. Rather, courts are finding ways to accommodate both the new individual right as well as compelling interests like public safety.

It’s not the world that gun control advocates would wish for. But it looks a lot like “normal” constitutional law. In the decade since Heller, the justices have declined dozens of opportunities to expound on the right to keep and bear arms, choosing not to grant certiorari (that is, agree to hear cases), with only two exceptions.

In 2010’s McDonald v. City of Chicago, the Court made the Second Amendment applicable to state and local regulations — a significant decision in practical terms, since state and local laws constitute the bulk of firearms regulation. And in a short, unsigned 2016 opinion, the Court vacated the Massachusetts Supreme Judicial Court’s upholding of a stun gun ban.

The Court’s unwillingness to hear another gun rights case recently led a frustrated Justice Thomas, who voted with the majority in Heller, to call the Second Amendment a “constitutional orphan.”

But that’s a misreading of the evidence. the Supreme Court does not have sole responsibility for the development of constitutional doctrine. Vastly more constitutional questions are resolved in lower courts, including the federal courts of appeals, than in the Supreme Court. And when those courts reach agreement on legal issues, the justices are generally less inclined to intervene.

Those lower courts have resolved more than 1,000 Second Amendment challenges in the past 10 years. This makes it possible, even as the Supreme Court stays above the fray, to say something about the law governing the right to keep and bear arms.

In our new study, we coded every available Second Amendment decision (state and federal, trial and appellate) from Heller through February 1, 2016. For each individual Second Amendment challenge, we asked roughly 100 questions about the content of the challenge, the result, and the court’s methodology. We assembled more than 100,000 data points, allowing us to paint a picture of where Second Amendment law stands today.

Most Second Amendment claims fail

Any time a litigant raises a Second Amendment claim, he or she is arguing that a particular government action, typically a gun regulation, is unconstitutional. It is by now well-recognized that the vast majority of these claims have failed, and our data confirms it. Gun rights and gun regulation groups both regularly note this fact — though they draw very different conclusions.

For advocates of strong gun rights, the low success rate is fodder for the view that courts are hostile to the Second Amendment. Scholars, too, sometimes suggest that lower courts are flouting Scalia’s opinion or narrowing it from below.

Our data suggests alternative explanations, beginning with the objective weakness of many Second Amendment claims.

Most Second Amendment claims fail because of Heller itself

The merit, or lack thereof, of a Second Amendment challenge obviously correlates with success or failure. Strong claims should succeed at a higher rate than weak ones.

That may sound tautological, but a closer look at the data suggests that lower courts are using Heller to judge which claims are strong and which are weak. To be sure, “strength” and “weakness” will often be a matter of opinion, but the language of Heller makes it clear that some kinds of claims are flawed from the outset. Indeed, 60 percent of the judicial decisions in our data set quote, at least in part, the passage in Scalia’s opinion in which he explains that the Second Amendment, “[l]ike most rights, … is not unlimited.” Scalia went on to write:

Although we do not undertake an exhaustive historical analysis today of the full scope of the Second Amendment, 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.

This language from Heller gives constitutional blessing to a potentially wide range of regulation. So it should be unsurprising that the vast majority of the cases citing it go on to reject the Second Amendment claim and uphold the challenged law. Even when courts do not explicitly cite this particular passage in upholding gun laws, they often rely on other precedents that do so. That explains why the percentage of cases citing it has been steadily declining, as courts start to cite their own prior decisions that incorporate Heller’s list of exceptions.

The frequency of citations to the “longstanding prohibitions” passage helps explain why the success rate for Second Amendment claims is so low. For example, 24 percent of the challenges in our set are to felon-in-possession laws, which Scalia specifically singled out as appropriate; of those, 99 percent are losers.

What’s more, nearly three-quarters of the challenges in our data set — 742 of 1,153 — involve criminal cases, where the success rate of constitutional claims can be expected to be lower. Unlike civil litigants, who may have a choice of whether to be in court at all, and who are more likely to be paying their own lawyers, criminal defendants facing serious charges have every incentive to make whatever arguments they can get away with.

That kind of kitchen sink approach, combined with the fact that many criminal laws involving guns fall within the categories Scalia identified, lead to a low rate of success of Second Amendment claims in criminal cases: 6 percent overall.

Second Amendment doctrine incorporates tools commonly used throughout constitutional law

Our data shows that courts deciding Second Amendment challenges are drawing on tools common to other areas of constitutional law. This suggests that courts are normalizing the post-Heller Second Amendment and treating it like other constitutional rights: It’s subject to exceptions, some of which are derived from history, and to regulations that further certain important government interests. Courts continue to give considerable weight to the undeniable public safety concerns that animate most gun regulation.

In the immediate aftermath of Heller, it was not clear what form of doctrine would apply to the Second Amendment. But the 1,000 cases since Heller show courts using the basic tools of analysis familiar to constitutional lawyers.

Borrowing in part from First Amendment doctrine, for example, almost every federal court of appeal has adopted a two-part test that first asks whether the relevant person, weapon, or activity falls within the scope of the Second Amendment. As noted above, hundreds of Second Amendment cases — those involving felons or people with mental illness, for example — lose at this step.

Concealed carry, too, has been excluded from constitutional coverage, in keeping with Scalia’s observation in Heller that “the majority of the 19th-century courts to consider the question held that prohibitions on carrying concealed weapons were lawful under the Second Amendment or state analogues.”

If the case makes it past step one, the courts go on to ask whether the challenged law is constitutional in light of both the burden it imposes on the right to keep and bear arms and the public interest it furthers.

Even at this point, plaintiffs asserting a right to bear arms face a high hurdle because the public interest in these cases is almost always public safety: Weapons, and especially lethal weapons, pose an obvious risk if misused.

That’s not to say that every law will be properly tailored to further that public interest, and the laws that have been struck down have tended to be those that are overbroad or otherwise go “too far.” In Moore v. Madigan, for example, the US Court of Appeals for the Seventh Circuit struck down Illinois’s statewide ban on public carry.

But just as in other areas of law, judges in Second Amendment cases tend to give some deference to the policy choices and expertise of elected officials.

As a matter of methodology, then, the Second Amendment looks increasingly like “normal” constitutional law, which in turn can explain one reason so many challenges to weapons laws fail.

In much of the country, there are very few gun laws to challenge. That’s a political as much as a constitutional issue.

We have argued elsewhere, including at Vox, that discussions about the scope and strength of the Second Amendment should take account of local and regional variation when it comes to gun rights and regulation.

In keeping with those arguments, our data set shows that in the decade since Heller, Second Amendment challenges (and successes) are not evenly distributed throughout the country. Two courts, the Fourth and Ninth Circuits, account for about one-third of the challenges in the federal courts of appeal. Four states account for 68 percent of the state appellate challenges.

Gun rights advocates have had more success in those courts, both in absolute terms and proportionally. The most obvious cause of this regional variation is that the circuits and states with the most Second Amendment litigation, and the most Second Amendment successes, are those that already have comparatively stringent gun control. Federal laws apply nationally and impose some important restrictions (including the felon ban discussed above), but in many parts of the United States, there simply aren’t many gun laws to challenge.

That again helps explain the low success rate of Second Amendment litigation; there simply isn’t a lot of low-hanging fruit for gun rights litigators. The Second Amendment doesn’t have much work to do, it appears, because gun politics prevent most stringent regulations from being enacted in the first place. When DC’s and Chicago’s handgun bans were struck down in Heller and McDonald, for example, they were the only two such laws on the books in major American cities.

That suggests that gun laws in the US face political hurdles as much as they do constitutional hurdles.

Second Amendment litigation shows no signs of slowing down

Despite the overall failure rate, litigation rates have not decreased in the 10 years since Heller. That’s surprising in many ways. Since Heller represented a sea change in the law, one might expect an initial spike in litigation, as gun owners rushed to test the constitutionality of existing laws and the breadth of the Court’s holding. (The lawsuit that led to McDonald was filed the day Heller was decided.)

That surge would establish the new contours of the law, after which lawsuits would decrease as regulators and litigants came to accept the new status quo. Similarly, one might expect a high rate of initial success in those challenges, as gun laws across the country first became subject to the “individual right” reading of the Second Amendment, followed by a tapering off of success as those laws were struck down.

However, litigation rates remained consistent and high, and the rate of success increased during the period of our study. Our data alone cannot explain these counterintuitive trends, but it is possible that some litigants have failed to internalize consensus about what makes for a successful challenge, while others have adapted to bring better cases.

Others, perhaps, are content to fling themselves against Heller’s limitations and to hold up their failures as evidence that they must try harder — winning politically by losing in court.

The Second Amendment remains fertile territory for constitutional litigation and scholarship. The Second Amendment still faces foundational uncertainties with regard to a wide range of doctrinal and theoretical questions — far more so than the First Amendment, which has generated a century’s worth of case law and scholarship. For lawyers and scholars interested in the Second Amendment, this is an exciting time.

But the Second Amendment is no longer “terra incognita,” as one federal judge put it after Heller. Our data helps to map the post-Heller territory, and our hope is that it might help bring some much-needed clarity not only to the law but to the broader gun debate.

Joseph Blocher is a professor at Duke Law School. Eric Ruben is an adjunct professor at New York University School of Law and a fellow at the Brennan Center for Justice. They are the authors of “From Theory to Doctrine: An Empirical Analysis of the Right to Keep and Bear Arms After Heller,” which appeared in the Duke Law Journal.

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