On Monday, the U.S. Supreme Court declined to hear a challenge by the National Rifle Association's Illinois chapter that sought to overturn a Chicago suburb’s ban on some of the most common semi-automatic guns. Though two pro-gun justices—Antonin Scalia and Clarence Thomas—dissented, the biggest takeaway was largely left unsaid in this gun control victory.

In what’s been a pattern since it ruled in 2008 that people have the right to a handgun at home for self-defense, the Court left yet another major gun-control area unanswered. The justices might have heard the case and begun to rule if people could have militarized weapons at home, or if and how they could be carried in public, or if the government could require training. They avoided all of that.

That larger gun policy vacuum, in tandem with local gun laws being upheld by lower federal courts, is a snapshot of the gun control movement in America today. What’s new—and this differs from when Barack Obama ran for president in 2012 and 2008—is not just that local gun control efforts are being sustained, especially when they stop short of absolute gun bans. It’s also the realization that even without new federal laws or Supreme Court action, gun controls are moving ahead state by state.

“It’s easy to fall back on the conventional wisdom that gun politics never change,” said a press memo sent this week by Everytown for Gun Safety, a national gun control group, in response to the recent mass shootings in San Bernardino and Colorado Springs.

Everytown countered that 2015 saw a lot of progress at the local level. Oregon became the 18th state to require background checks for handguns sales. Nine states enacted laws to keep “guns out of the hands of dangerous [domestic] abusers.” Governors in three purple or red-leaning states—New Hampshire, Montana and West Virginia—defied the NRA and vetoed bills that dismantled “state concealed carry permitting systems.” Gun-control advocates stopped bills in 16 states that could have “let people carry concealed, loaded handguns in public with no permit.” They blocked bills in 16 states allowing guns on college campuses. They stopped legislation in 15 states allowing guns in K-12 schools.

“The gun lobby learned a tough lesson in 2015: when you go toe-to-toe with gun safety advocates, you lose,” Everytown concluded. “And looking ahead to the 2016 presidential election, we’ll continue… to ask a simple question, ‘What will you do to prevent gun violence that kills 88 Americans every day?'"

When it comes to the prospects for gun control in America, there are two main arenas. There's the political world, which is where advocates like Everytown are seeing progress. And there's also the more bogged-down legal world, where the Constitution’s Second Amendment and 43 state constitutions grant fundamental gun rights along with clear government authority to regulate guns.

Until very recently, there has been a bit of stalemate between these spheres. In the political world, too many members of Congress, including Democrats, and President Obama when he was running in 2012 and 2008, were afraid of fighting the NRA or didn’t want to discuss gun control. At the same time, until the Supreme Court issued its 2008 ruling, Heller, which overturned Washington, D.C.’s compete handgun ban and granted the right to keep a handgun at home for self-defense, the Court had not made a major Second Amendment decision in decades. (It also ruled in 2010 that the Second Amendment applied to the states.)

The NRA likes to say there are 20,000 gun laws on the books in America, but the current Supreme Court has only addressed the specific issue of handguns at home. That illustrates the legal vacuum gun control advocates have been filling with state-based controls that target varying slices of gun culture, such as Everytown’s list of 2015 achievements. But something else has been happening recently that is shaking up the stalemate on adopting new gun laws across America.

The gun control movement has become energized in the past two to three years, and now—at least on the Democratic side—all the presidential candidates are calling for sweeping controls. “I don’t think the problem is the Constitution and Second Amendment,” said Adam Winkler, a UCLA law professor and expert on gun control. “It’s a question of political activity and political mobilization.”

In highly regarded books, Winkler has explained that there is a constitutional basis for gun rights and gun controls. In recent decades, due to the NRA’s lobbying and electoral machine, the political world has paid more attention to the gun rights side of the equation. On the other hand, federal courts have mostly upheld gun control laws that were not total prohibitions, Winkler said, underscoring that it is increasingly possible to regulate guns.

Still, it would be naÃ¯ve to believe that the 300 million guns in America are somehow going to vanish, or be bought up by the government, he said. That's because the backdrop behind the politics of gun control is the legal reality that the U.S. Constitution and nearly all state constitutions protect individual gun rights and government power to regulate guns.

The Second Amendment, as most people know, creates the right to “keep and bear” arms, meaning to own guns and carry in public. Similar wording appears in 43 state constitutions. It hardly matters that the political rationale for these rights has changed with the times. The Supreme Court’s 2008 Heller ruling affirmed a right to a handgun at home for self-defense. The rationale for gun rights before the Civil War was retaining state power against a federal government—especially to preserve slavery as an institution, dominate slaves and conquer Native Americans. The Second Amendment’s other key phrase, a “well-regulated” militia, is the basis for gun control laws, granting authority to regulate guns.

Legal experts say that second right—government's authority—has been more vaguely articulated. There is not a comparable body of firearms law to the First Amendment’s right of free speech, for example, where decades of court decisions have defined “time, place and manner” restrictions. (Free speech does not include yelling fire in a theater or protesters going into courthouses, for example.)

The modern gun lobby wants as little regulation as possible—especially at the national level. One result is what was seen in Monday’s Supreme Court decision not to hear a challenge to a Chicago suburb’s semi-automatic ban. While it gave local gun control advocates a victory, the Court did not take up the larger issue of regulating these arms nationally. It hasn’t ruled at all on militarized weapons.

Winkler said the Court has only ruled on “one or two” questions concerning modern gun culture. “There’s a right to a handgun in a home for self-defense. But it left every other question open.” He said they did not take up whether there is a right to an assault weapon in a home, or what can be carried in public, or where these weapons can be prohibited in public.

“The Second Amendment is not an unlimited right—it isn’t a libertarian right to have it all,” he said in a recent National Constitution Center debate with George Mason University Law School’s Nelson Lund, a conservative gun scholar. “There’s plenty of leeway for government to regulate, but not destroy the right.”

Lund agreed, but wanted to see the least government assertion. “That private, individual right has to be reconciled with legitimate interests of government with public safety," he said. But "courts have to develop it into rights with specifics—not absolutes.”

Thus, the bottom line with gun controls in 2015 is how far can government can go. The most sweeping controls—like the District of Columbia banning all handguns—are now impossible, given the Supreme Court’s Heller ruling. And so the political battle shifts to state legislatures and city councils where the fight is over the fine print of policies: buyer background checks, bans for domestic violence offenders, adopting or repealing concealed-carry laws, allowing guns onto school grounds, and permit and training requirements—or the lack of them.

There has been much news coverage of public anxiety following recent mass shootings. What’s not been widely covered is the legal landscape regulating guns, which has many blanks that are yet to be filled in. That was underscored by the Supreme Court’s decision Monday to turn away Highland Park's assault rifle ban. If gun control remains an issue throughout the rest of the 2016 campaign, then depending on who is elected there may be a different political climate to accomplish something bigger than state-by-state reform.