The Supreme Court just dramatically expanded Americans’ right to bear arms. In a 6-3 opinion, with the court’s Republican-appointed justices in the majority, the court ruled that a New York law that heavily restricts the ability to carry a concealed handgun in public violates the Constitution. 

This decision is a big deal. Previously, the court had only said that the Constitution protected the ability to have a gun inside the home for self-defense. In that decision, which came down in 2008, the justices didn’t rule on how guns carried outside the home could be regulated. It took almost 15 years for the justices to come back to that question, but now they have. The Second Amendment “protect[s] an individual’s right to carry a handgun for self-defense outside the home,” wrote Justice Clarence Thomas in the majority opinion for Thursday’s ruling. Laws like New York’s, which required people who wanted a license to carry a concealed handgun in public to show they have a good reason, are no longer allowed.

That doesn’t mean there is no way to regulate the carrying of guns in public — Justice Brett Kavanaugh said that explicitly in his concurring opinion. But Thursday’s ruling does change the way regulations are evaluated. Thomas’s opinion states regulations need to be historically consistent with the Second Amendment. That means when they look at a modern gun regulation, judges will have to figure out if another, reasonably similar law was passed earlier in the country’s history. Previously, courts had also considered whether a regulation could be justified for other reasons, but that second layer of consideration is no longer allowed.

What all of this means in practice, though, will have to be worked out by the lower courts, which means there will likely be a flood of new litigation over gun restrictions that could come right back to the Supreme Court.

The decision is a big expansion of gun rights

Gun rights advocates have been waiting for over a decade for this ruling – and it did not disappoint. Thomas, who has been complaining for years about the court’s reticence to clarify the meaning and scope of the Second Amendment, wrote a sweeping opinion that expands gun rights significantly, and could have a big impact on Americans’ lives.

That’s because the 2008 opinion, while it transformed the way that the Second Amendment is interpreted to include an individual right to bear arms, didn’t actually change the status quo very much. There were relatively few laws that restricted the ability to have a gun at home, and the justices were clear that the opinion didn’t extend further. A study that looked at lower court rulings on Second Amendment challenges from 2008 to 2016 found that the Supreme Court’s opinion didn’t really change the way other judges were ruling on gun regulations (though, the study acknowledged, that could also be due in part to the types of cases under consideration).

Before Thursday’s ruling, judges had two factors to consider when evaluating the constitutionality of a gun regulation: Does it fit with the history of the Second Amendment? And does the state have another reasonable justification — like social science data suggesting that the law could reduce gun violence? 

Under the new ruling, state governments can no longer argue that a gun restriction should be upheld because it serves an important interest. Instead, judges will only consider whether “the regulation is consistent with this Nation’s historical tradition of firearm regulation.” In his opinion, Thomas noted that modern regulations don’t have to be a “dead ringer for historical precursors.” But as gun law experts have pointed out, figuring out whether modern gun regulations are similar enough to laws that were passed 200 years ago won’t be a simple matter. The ruling opens the door for every gun regulation that was upheld under the 2008 ruling to be challenged again — in a judiciary that is much more conservative than it was even a few years ago.

New battle lines in the war over gun laws

As with many Supreme Court rulings, we won’t understand the full implications of today’s ruling for a long time. Five other states and the District of Columbia have laws like New York’s, and they will have to pass new regulations for people who want to carry handguns in public. That in itself is not a small thing, since the states include California, New Jersey and Massachusetts, which are populous states with big cities. 

But the conservative justices could have gone further and cut down a huge swath of gun regulations at once, which they did not. “Our holding decides nothing about who may lawfully possess a firearm or the requirements that must be met to buy a gun,” Justice Samuel Alito wrote in his concurring opinion. “Nor does it decide anything about the kinds of weapons that people may possess.”

The ruling does, however, create a bunch of new opportunities for advocates who want to limit states’ ability to determine who can carry a gun and where. In his opinion, Thomas said that guns can still be banned in “sensitive places,” but didn’t expand much further on what a “sensitive place” actually is. In his dissent, Justice Stephen Breyer pointed out that with a historical approach, this category could turn out to be pretty limited. “Where does that leave the many locations in a modern city with no obvious 18th- or 19th-century analogue?” he wrote. “What about subways, nightclubs, movie theaters, and sports stadiums?”

So the future will depend, at least in part, on what state lawmakers try to do. Lawmakers in a state like New York or California could test the limits of the Supreme Court’s ruling by designating the subway, Broadway theaters or grocery stores as “sensitive places” where heightened restrictions can be applied. The risk for them, of course, is that the next Supreme Court ruling could expand gun rights even further.