Three people were killed and another injured in a mass shooting at the University of Nevada, Las Vegas on Wednesday.

The shooter, a former college professor in his 60s who reportedly had applied for a job at the university, was killed in a shootout with police. Further details about his motive and the gun used in the attack were not immediately known.

The shooting was one of several hundred mass shootings this year, and it took place not far from the site of the deadliest mass shooting in modern US history, in which 58 people were killed and hundreds others injured at a Las Vegas music festival in 2017.

No other high-income country has suffered such a high death toll from gun violence. Every day, 120 Americans die at the end of a gun, including suicides and homicides, an average of 43,375 per year. According to the latest available analysis of data from 2015 to 2019, the US gun homicide rate was 26 times that of other high-income countries; its gun suicide rate was nearly 12 times higher. Mass shootings, defined as attacks in which at least four people are injured or killed excluding the shooter, have been on the rise since 2015, peaking at 686 incidents in 2021. There have been 632 mass shootings in the US in 2023 as of early December, including the Las Vegas shooting, and at the current pace, the US is set to eclipse the 2021 record this year.

Despite that sheer carnage, however, the political debate over how to ensure that guns don’t fall into the hands of people who may hurt themselves and others has long proved intractable. Last year, Congress reached a deal on limited gun reforms for the first time in nearly 30 years in the wake of a shooting at an elementary school in Uvalde, Texas — the deadliest school shooting since 2012.

But those narrow reforms clearly haven’t stopped America’s gun violence epidemic. The US’s expansive view of civilian gun ownership has been so ingrained in politics, in culture, and in the law since the nation’s founding that there’s no telling how many more people will die before federal lawmakers take further action. In that absence, many red states have loosened their gun laws over the last few years, rather than making it harder to obtain a gun.

“America is unique in that guns have always been present, there is wide civilian ownership, and the government hasn’t claimed more of a monopoly on them,” said David Yamane, a professor at Wake Forest University who studies American gun culture.

The US has a lot of guns, and more guns mean more gun deaths

It’s hard to estimate the number of privately owned guns in America since there is no countrywide database where people register whether they own guns, there is a thriving black market for them in the absence of strong federal gun trafficking laws, and people can manufacture their own guns with DIY kits or 3D printers. The gun lobby has also vehemently opposed federal legislation to track gun sales and establish a national handgun registry.

One estimate from the Small Arms Survey, a Swiss-based research project, found that there were approximately 390 million guns in circulation in the US in 2018, or about 120.5 firearms per 100 residents. That number has likely climbed in the years since, given that one in five households purchased a gun during the pandemic, though the 2018 estimate remains the most recent available. There has also been a significant increase in the number of guns manufactured and imported in the years since. But even without accounting for that increase, US gun ownership is still well above any other country: Yemen, which has the world’s second-highest level of gun ownership, has only 52.8 guns per 100 residents; in Iceland, it’s 31.7.

Scott Olson/Getty Images

American guns are concentrated in a tiny minority of households: just 3 percent own about half the nation’s guns, according to a 2016 Harvard and Northeastern University study. They’re called “super owners” who have an average of 17 guns each. Gallup, using a different methodology, found that 45 percent of Americans lived in a household with guns in 2022.

Researchers have found a clear link between gun ownership in the US and gun violence, and some argue that it’s causal. One 2013 Boston University-led study, for instance, found that for each percentage point increase in gun ownership at the household level, the state firearm homicide rate increased by 0.9 percent. And states with weaker gun laws have higher rates of gun-related homicides and suicides, according to a study by the gun control advocacy group Everytown for Gun Safety.

The link between gun deaths and gun ownership is much stronger than the link that gun rights advocates often seek to draw between violence and mental health issues. If it were possible to cure all schizophrenia, bipolar, and depressive disorders, violent crime in the US would fall by only 4 percent, according to a study from Duke University professor Jeffrey Swanson, who examines policies to reduce gun violence.

There’s still a pervasive idea, pushed by gun manufacturers and gun rights organizations like the National Rifle Association, that further arming America is the answer to preventing gun violence — the “good guy with a gun” theory. But there have been relatively few instances in which police or armed bystanders have been able to successfully stop an active attack.

According to a database maintained by Advanced Law Enforcement Rapid Response Training Center at Texas State University, there were 520 active attacks — defined as when one or more people are “actively killing or attempting to kill multiple unrelated people in a public space,” including but not limited to shootings — between 2000 and 2022. In many of those cases, police were unable to stop the attacker, either because the attack had already ended by the time they arrived or because the attacker surrendered or committed suicide. Only in 160 cases were police able to successfully intervene by shooting or otherwise subduing the attacker.

Another 2021 study from Hamline University and Metropolitan State University found that the rate of deaths in 133 mass school shootings between 1980 and 2019 was 2.83 times greater in cases where there was an armed guard present. The researchers argue the results suggest the presence of an armed guard increased shooters’ aggression and that because many school shooters have been found to be suicidal, “an armed officer may be an incentive rather than a deterrent.”

“The idea that the solution to mass shootings is that we need more guns in the hands of more people in more places so that we’ll be able to protect ourselves — there’s no evidence that that’s true,” Swanson said.

The prevalence of the self-defense narrative is part of what sets apart the gun rights movement in the US from similar movements in places like Canada and Australia, according to Robert Spitzer, a professor at SUNY Cortland who studies the politics of gun control.

Self-defense has become by far the most prominent reason for gun ownership in the US today, eclipsing hunting, recreation, or owning guns because they’re antiques, heirlooms, or work-related. That’s also reflected in ballooning handgun sales, since the primary purpose of those guns isn’t recreational, but self-defense.

American gun culture “brings together the hunting-sporting tradition with the militia-frontier tradition, but in modern times the hunting element has been eclipsed by a heavily politicized notion that gun carrying is an expression of freedom, individuality, hostility to government, and personal self-protection,” Spitzer said.

Chandan Khanna/AFP via Getty Images

That culture of gun ownership in the US has made it all the more difficult to explore serious policy solutions to gun violence after mass shootings. In high-income countries lacking that culture, mass shootings have historically galvanized public support behind gun control measures that would seem extreme by US standards.

Canada banned military-style assault weapons two weeks after a 2020 mass shooting in Nova Scotia. In 2019, less than a month after the Christchurch massacre, New Zealand lawmakers passed a gun buyback scheme, as well as restrictions on AR-15s and other semiautomatic weapons, and they later established a firearms registry. The 1996 Port Arthur massacre in Australia spurred the government to buy back 650,000 firearms within a year, and murders and suicides plummeted as a result.

By contrast, nearly a decade went by after the 2012 school shooting at Sandy Hook Elementary School in Newtown, Connecticut, before Congress passed a new gun control law. The Bipartisan Safer Communities Act, the law passed in June 2022, was relatively limited: It incentivized states to pass red flag laws, enhanced background checks for gun buyers under 21, and closed the “boyfriend loophole,” which allowed some people with domestic violence convictions to purchase guns. But it did not ban any types of weapons, and certain studies suggest that even truly universal background checks may have limited effects on gun violence.

At the same time, many states have sought to expand gun ownership in recent years. At least 27 states have now passed laws allowing residents to carry a handgun without a permit and allow school staff and teachers to carry guns on campus.

“Other countries look at this problem and say, ‘People walking around in the community with handguns is just way too dangerous, so we’re going to broadly limit legal access to that and make exceptions on the margins for people who might have a good reason to have a gun,’” Swanson said. “Here we do just the opposite: We say that, because of the way that the Supreme Court interpreted the Second Amendment, everybody has the right to a gun for personal protection, and then we tried to make exceptions for really dangerous people, but we can’t figure out who they are.”

While the majority of Americans support more gun control restrictions, including universal background checks, a vocal Republican minority unequivocally opposes such laws — and is willing to put pressure on GOP lawmakers to do the same. Alongside the NRA, and a well-funded gun lobby, this contingent of voters sees gun control as a deciding issue, and one that could warrant a primary challenge for a lawmaker who votes for it.

The gun lobby has the advantage of enthusiasm. “​​Despite being outnumbered, Americans who oppose gun control are more likely to contact public officials about it and to base their votes on it,” Barnard College’s Matthew Lacombe explained in 2020. “As a result, many politicians believe that supporting gun regulation is more likely to lose them votes than to gain them votes.”

Sarah Reingewirtz/MediaNews Group/Los Angeles Daily News via Getty Images

The Supreme Court has made it impossible to cure America’s gun violence epidemic

In 2008, the Supreme Court effectively wrote NRA CEO Wayne LaPierre’s “good guy with a gun” theory into the Constitution. The Court’s 5-4 decision in District of Columbia v. Heller (2008) was the first Supreme Court decision in American history to hold that the Second Amendment protects an individual right to possess a firearm. But it also went much further than that.

Heller held that one of the primary purposes of the Second Amendment is to protect the right of individuals — good guys with a gun, in LaPierre’s framework — to use firearms to stop bad guys with guns. As Justice Antonin Scalia wrote in Heller, an “inherent right of self-defense has been central to the Second Amendment right.”

As a matter of textual interpretation, this holding makes no sense. The Second Amendment provides that “a well regulated Militia, being necessary to the security of a free State, the right of the people to keep and bear Arms, shall not be infringed.”

We don’t need to guess why the Second Amendment protects a right to firearms because it is right there in the Constitution. The Second Amendment’s purpose is to preserve “a well-regulated Militia,” not to allow individuals to use their weapons for personal self-defense.

For many years, the Supreme Court took the first 13 words of the Second Amendment seriously. As the Court said in United States v. Miller (1939), the “obvious purpose” of the Second Amendment was to “render possible the effectiveness” of militias. And thus the amendment must be “interpreted and applied with that end in view.” Heller abandoned that approach.

Heller also reached another important policy conclusion. Handguns, according to Scalia, are “overwhelmingly chosen” by gun owners who wish to carry a firearm for self-defense. For this reason, he wrote, handguns enjoy a kind of super-legal status. Lawmakers are not allowed to ban what Scalia described as “the most preferred firearm in the nation to ‘keep’ and use for protection of one’s home and family.”

This declaration regarding handguns matters because this easily concealed weapon is responsible for far more deaths than any other weapon in the United States — and it isn’t close. In 2021, for example, a total of 14,616 people were murdered in the US, according to the FBI. Of these murder victims, at least 5,992 — just over 40 percent — were killed by handguns.

Allison Dinner/AFP via Getty Images

In 2021, the Supreme Court made it even harder for federal and state lawmakers to combat gun violence. In its decision in New York State Rifle & Pistol Association v. Bruen, it massively expands the scope of the Second Amendment, abandons more than a decade of case law governing which gun laws are permitted by the Constitution, and replaces this case law with a new legal framework that, as Justice Stephen Breyer writes in dissent, “imposes a task on the lower courts that judges cannot easily accomplish.”

Bruen has since allowed handguns — which are responsible for the overwhelming majority of gun murders in the United States — to proliferate on many American streets. That’s because Bruen strikes the types of laws that limit who can legally carry handguns in public, holding that “the Second and Fourteenth Amendments protect an individual’s right to carry a handgun for self-defense outside the home.” Amid a flurry of activity in the courts over the last year, more than a dozen state and federal gun control laws have been invalidated in whole or in part as a result.

Under this new legal regime, the future of firearm regulation looks grim for anyone who believes that the government should help protect us from gun violence.

Update, December 7, 2023, 11:25 am: This story was originally published on May 26, 2022, and has been updated multiple times, most recently with the latest details from the December 6 shooting in Las Vegas.