THE BILL OF RIGHTS is 228 years old, but it has been only 11 years since America's Supreme Court recognised an individual right to bear arms in District of Columbia v Heller. The 5-4 ruling spanned 157 pages and turned on a historical dispute: whether the Second Amendment guarantee of “the right of the people to keep and bear arms” was understood in 1791 only in the context of militia service—as the amendment’s preface suggests—or embraces an individual’s liberty to hold weapons for “traditionally lawful purposes, such as self-defence within the home”. The more expansive vision won the day, but Justice Antonin Scalia’s opinion left many questions unresolved—what other “lawful purposes” apply, which types of firearms are protected, how assiduously gun possession may be regulated without offending the constitution. Acknowledging that Heller did not quite leave the contours of the right in “a state of utter certainty”, Justice Scalia reassured America that there “will be time enough to expound upon” its nature in future cases.

Few believed in 2008 that it would take over a decade for another challenge to a gun regulation to appear before the justices. Other than McDonald v Chicago two years later, in which the court said that states and cities (and not only the federal government) are bound by the Second Amendment, the justices have flicked away case after case challenging firearm regulations. That dry period for gun-rights advocates ended on January 22nd, when the justices agreed to hear New York State Rifle & Pistol Association Inc. v City of New York, a challenge to a law prohibiting gun owners from “transporting licenced, locked up, and unloaded handguns to any place outside the city”. With a “premises” licence, New Yorkers may have a gun in their home and may carry their weapon (unloaded) to one of seven shooting ranges within city limits. But crossing the Hudson River into New Jersey or venturing north to Westchester County with a gun is a violation of the transport law—unless you have a hard-to-come-by licence to carry a weapon outside the premises of your home.

The petitioners contend that these restrictions are needlessly onerous. Gun owners may have a second home to which they would like to bring their guns or they might prefer a shooting range outside the city. The law “is an extreme and irrational outlier that does not even make sense on its own terms”, the lawyers for the petitioners write. New York City, they argue, violates not only the Second Amendment but also the Commerce Clause of Article I, Section 8—which prohibits discrimination against out-of-state businesses—and strips individuals of the right to travel freely across city and state lines.

New York City responds that the law promotes a “compelling governmental interest in protecting public safety” and “minimises the risk of gun violence”. The petitioners’ plea, the city says, is misplaced, as the rule “neither infringes upon their Second Amendment rights nor on their fundamental right to travel. It only restricts their ability to transport firearms that are specifically licensed for possession and use inside their New York City residences through the city for the purpose of bringing them to shooting ranges or homes outside the city”. The liberty to carry a gun anywhere one likes, New York City concludes, “is not a fundamental right”.

The outcome of New York State Rifle & Pistol would be hard to predict just by looking at the decision in Heller. The city, after all, does protect an individual’s right to bear arms for self-defence. It just puts limits on carrying weapons outside one’s home. Justice Scalia emphasised that nothing in Heller “should be taken to cast doubt” on laws banning felons or mentally ill people from possessing firearms. Carrying guns “in sensitive places such as schools and government buildings” can be banned, too, and only weapons “in common use at the time” fall under its umbrella. But the lacunae in Heller leave a lot of room for interpretation. Gun-rights jurisprudence was in its infancy in 2008; 11 years later, it has barely entered toddlerhood. The Second Circuit Court of Appeals upheld New York's law, citing Heller’s line that the right to bear arms is paramount in “the home, where the need for defence of self, family, and property is most acute”. But does this apply only within one’s primary residence? Or does the constitution permit a city resident to tote his weapon with him when venturing to his country house, as one of the New York State Rifle & Pistol plaintiffs wanted to do?

Examining precedent is only one way to assess how the court will rule. Listening to what the justices have said is a more dependable strategy. It has been clear for a while that Justice Clarence Thomas wants a much more robust Second Amendment. He has lamented in several dissents his colleagues’ refusal to take up challenges to gun laws. Last February, when the justices declined to hear a challenge to a California law requiring a 10-day waiting period to buy a gun, Justice Thomas wrote that the right to bear arms “is apparently this court’s constitutional orphan”. In 2010, Justice Samuel Alito criticised efforts to demote the liberty to a mere "second-class right". The court’s newest member, Justice Brett Kavanaugh, has been similarly solicitous of gun-rights claims. In his Senate confirmation hearings last September, he defended his view that banning semiautomatic rifles violated the constitution because they are “are in common use by law-abiding citizens”.

With two other justices friendly to gun rights, New York City’s somewhat weakly justified transport law may be the new conservative majority’s key to expanding Heller. But the question is how they will do it when the case comes before them in the autumn. Justice Scalia’s opinion in 2008 noted that at America's founding, English subjects saw the right to bear arms as “fundamental”—a designation that theoretically makes it difficult to regulate. But he did not specify which standard of review the court should apply when determining if a law may violate it. If the court rules that New York’s rule does not serve even minimally rational purposes—a point pressed by the petitioners—it may not need to create a more demanding apparatus to evaluate other regulations and the decision may have only limited implications outside the Big Apple. But if Justice Thomas persuades his colleagues to craft an opinion elevating gun rights to co-equal status with the freedom of speech and religious liberty, New York City’s law will be only the first casualty. Gun regulations of all sorts around the country—from bans on semiautomatics to regulations of concealed weapons—could be in grave trouble just as the 2020 presidential election enters a high gear.