If the key gun control proposals now being considered in Congress had been law since 1999, four gunmen younger than 21 would have been blocked from legally buying the rifles they used in mass shootings. At least four other assailants would have been subject to a required background check instead of slipping through a loophole. Ten might have been unable to steal their weapons because of efforts to require or encourage safer gun storage. And 20 would not have been allowed to legally purchase the large-capacity magazines that helped them kill, on average, 16 people each.
Taken together, those four measures might have changed the course of 35 mass shootings — one-third of such episodes in the United States since the massacre at Columbine High School in Colorado, a New York Times analysis has found. Those 35 shootings killed a combined 446 people.
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But in a nation awash with guns, for every mass killing those limited reforms could plausibly have altered, another two would have been unaffected — either because assailants obtained their guns illegally or because they were older adults using weapons that would not have been subject to any proposed restrictions.
Another proposed measure, a ban on the sale of military-style semi-automatic guns known as assault weapons, could in theory have had greater effect. But it faces even tougher opposition than the other proposals. Congress banned the sale of such guns in 1994, but the law expired 10 years later, and the weapons have since surged in popularity. Weapons covered under the expired ban were used in 30% of the shootings in the data, causing nearly 400 deaths. In a speech Thursday, President Joe Biden asked Congress to renew the ban.
No law would be guaranteed to stop any one shooting, and the U.S. already has more guns than people, leaving a motivated individual with numerous paths to violence. But after recent massacres in Texas and New York state, which authorities said were committed by 18-year-old men who legally bought military-style rifles, Democrats have made emotional appeals to advance gun control legislation. “It’s time to act,” Biden said Thursday.
Republican leaders have dismissed many of the proposals as unfair or unconstitutional curtailments of law-abiding gun owners’ civil rights without clear evidence they would improve public safety.
“We all want to keep children safe in school, but this bill wouldn’t do that,” the ranking member of the House Judiciary Committee, Rep. Jim Jordan, R-Ohio, said during a hearing Thursday.
Researchers who study gun violence said that deterring one-third of mass shootings would be a substantial success, given the nation’s widespread gun ownership. “There’s no such thing as a perfect, 100% effective policy or suite of policies,” said Garen Wintemute, director of the Violence Prevention Research Program at the University of California at Davis. “But there is a chance to make a real difference.”
Several of the bills are unlikely to become law. To evaluate the range of possibilities, the Times analyzed a database of mass shootings kept by the Violence Project, a nonprofit group that has collected information about shootings in public places that have killed four or more people, not including the gunman. (This article’s definition of mass shooting is based on that standard. The database was last updated after the shooting in Buffalo, New York, and the Times added the more recent Texas shooting.)
No single policy in the analysis would have affected a majority of the shootings on its own. And the measure that seems most likely to achieve bipartisan support in the Senate — a broader background check law — would have had a clear influence on only a handful of shootings, according to the database. Measures to prevent gun thefts and to bar the sale of magazines that hold more than 10 bullets would have affected more shootings but appear less likely to become law.
An additional measure that the House will vote on this week and that is under discussion in the Senate would expand so-called red-flag laws in more states, establishing a legal process for removing guns from people in crisis. Depending on how those laws were structured and how widely they are used, they could make a bigger difference: In a startling 46% of shootings in the database, attackers had told someone about their intent to cause harm before the attacks. And in 36% of cases, an attacker had previously expressed suicidal intentions, another cause for possible gun removal under the laws.
But invoking such red-flag laws generally requires a court order, making it hard to know when they might have been used. They would also be easy to evade unless Congress also expanded background checks, which would prevent flagged people from simply buying new weapons. And the analysis showed the limits of such laws: Eight shootings were carried out by gunmen who were known to have previously threatened violence or suicide, even though they lived in states that already had a red-flag law.
A majority of the House supports a broad package of gun reforms and has already passed legislation to expand background checks. Other measures are expected to pass in a floor vote this week. But gun legislation faces an uphill battle in the Senate, where any measure will need the votes of 10 Republicans to overcome a legislative filibuster, even if every Democrat supports it.
Few Republican senators have signaled much enthusiasm for the bills, though a bipartisan group is negotiating over possible legislation. Some version of a red-flag law and some form of a background check have been part of those conversations so far.
Mass shootings account for a tiny share of the roughly 100 Americans who die on average every day from gun violence. But researchers say many of the measures under discussion to prevent mass shootings would also reduce other gun violence, including suicides.
Several of the measures are designed to close gaps in existing federal gun laws, which stop 18-year-olds from buying handguns but not assault rifles and require background checks for guns bought from a licensed dealer but not those bought from private sellers, often online or at gun shows. Other proposals, like regulations for gun storage and high-capacity magazines, do not currently exist in federal law.
Many states have already passed some or all of these policies already. But the patchwork of laws limits the effectiveness of such restrictions because gun purchasers can travel to a neighboring state with fewer rules. The authors of the House legislation have emphasized the value of national laws that would apply uniformly.
“They go to the states where it’s easy to buy guns, where there are practically no limitations, and then they take those guns to other states,” said Rep. Ted Deutch, D-Fla., who is a co-sponsor of multiple parts of the House package. “And this will just ensure that this can’t happen.”
In a House Judiciary Committee hearing on the legislation Thursday, Republican members rejected the proposed measures as ineffective.
“It is not kind and is not compassionate to tell people you are doing something to help them, when in fact you have no idea whether this legislation that you’ve fashioned would in fact do that,” said Rep. Matt Gaetz, R-Fla. “I would suggest that it’s potentially cruel that they’ve inspired a response to a tragedy when in fact that response won’t work.”
The National Rifle Association, the nation’s most influential gun lobby, opposes the package. In a news release Thursday, the group said the policies would harm the rights of law-abiding Americans “who have never, and will never, commit a crime.” A spokesperson for the group declined to comment on the Times analysis.
There is limited academic evidence about what policies could prevent mass shootings. A 2020 review of research on gun policies by the Rand Corp. drew few conclusions. But Andrew Morral, who led the project, said the absence of clear proof did not mean that policymaking would be fruitless. Mass shootings are much rarer than other forms of gun violence, making them hard to study. And some policies will never be easy to evaluate if they are not tried.
“It’s great if you have rigorous scientific evidence on which to base your policies, but that’s almost never true, and it’s an impossible standard,” he said. “When there’s no evidence there, it doesn’t mean the policies are not good. It only means the science isn’t good.”
Democrats are proposing several policies, with different prospects of becoming law. Here is what we learned about six of them.
Raising the Minimum Age to Purchase Certain Guns to 21
Four of the gunmen were younger than 21 and purchased their weapons legally.
Proposal: Federal law currently limits the ability of those younger than 21 to purchase handguns but does not stop those 18 and older from buying so-called assault rifles. A House proposal would raise the minimum gun-purchasing age to 21 for more weapons but not all. (Eighteen-year-olds would still be able to buy hunting rifles.)
Where it stands: The House is expected to pass the measure this week. Biden endorsed it in his speech. It does not appear to be the subject of current negotiations among senators. Republicans have called the provision unconstitutional, pointing to a recent ruling by the U.S. Court of Appeals for the 9th Circuit, which found that California’s ban on the sale of some semi-automatic weapons to adults younger than 21 violated the Second Amendment.
What the analysis shows: Most mass shooters in the database who legally purchased their guns were older than 21, but four of the gunmen might have been stymied by such a law.
Mass shootings by younger attackers may be becoming more common. All four mass shooters who legally bought guns before turning 21 conducted their attacks in the last five years.
Age-based restrictions may limit gun violence more generally, evidence suggests, even if they may not have prevented many mass shootings. Studies of state laws have shown they seem in particular to prevent suicides, which are a leading cause of death among young Americans.
Expanding Background Checks to Cover Private Sales
At least four attackers purchased a weapon from a private seller in a state where background checks were not required for such sales.
Proposal: Americans who buy guns from licensed dealers have to undergo a background check, but under federal law, such checks are not required when people buy guns from private sellers at gun shows or through online marketplaces. A bill that passed the House would make such checks more universal and give investigators more time to complete the check.
Where it stands: Biden has endorsed the House bill. A bipartisan group of senators is discussing a possible background check bill, but it may differ in its details or may not advance in any form.
What the analysis shows: Among the perpetrators of mass shootings in the database, four purchased guns from private sellers. One, the gunman in a 2019 shooting that killed seven people in Odessa, Texas, had already failed a background check before purchasing his weapon.
Several other attackers had backgrounds that should have prevented them from obtaining a gun, but the information was not uncovered during the check. The gunman in a 2017 shooting in Sutherland Springs, Texas, who killed 25 people in a church, had a domestic violence conviction that should have made him ineligible to purchase a gun, but it was never reported to the database.
No background check law can prevent all private gun transfers. Many people purchase guns from acquaintances or buy them using purchasers with no flags who were hired to obtain the weapons. But subjecting more gun purchases to background checks would make it harder for ineligible people to obtain guns through legal channels.
Encouraging Safe Gun Storage and Punishing People Who Fail to Secure Guns From Children and Criminals
Proposal: Measures before the House would impose requirements and incentives for safer gun storage, which could make guns harder to steal. The bill would also impose penalties for people who fail to secure a gun, but those would apply only to households where a minor “is likely to gain access” or where a person prohibited from owning a gun lives. Other provisions would teach the public about the benefits of safe storage and offer rebates for people who buy safety devices.
Where it stands: Biden endorsed the House bill in his speech. Safe gun storage legislation does not appear to be a topic of current Senate negotiations.
What the analysis shows: Ten percent of mass shootings involved weapons that were stolen. Several of those shootings have involved young assailants, including in 2012 at Sandy Hook Elementary School in Connecticut.
Banning the Sale of Large-Capacity Magazines
Proposal: The House is also considering a bill that would ban the purchase of ammunition magazines that hold more than 10 bullets.
Where it stands: The House is expected to pass the bill this week, and Biden endorsed it. Senate Republicans are seen as unlikely to advance the measure.
What the analysis shows: At least 19% of all shootings in the database involved large-capacity magazines, including several with the largest death counts.
A ban on large-capacity magazines might reduce the number of mass shootings by eliminating a tool that makes them seem possible to would-be gunmen, advocates say. They could also reduce the number of people shot, by requiring more frequent reloading.
The 2017 shooting of spectators at a country music concert in Las Vegas caused the greatest number of deaths of any event in the database; it involved several large-capacity magazines and a gun modification known as a “bump stock” that can make a semi-automatic weapon function more like a fully automatic machine gun. Without such tools, it is unlikely the gunman could have shot so many people.
Expanding Red-Flag Laws to Remove Guns From People in Crisis
In 47% of shootings, an attacker expressed interest in harming others. In 36%, at least one attacker was previously known to be suicidal.
The proposal: Nineteen states have passed laws that allow police and other citizens to seek a court order to temporarily confiscate guns from people who are deemed an immediate threat to themselves or others. Congress is considering legislation that might broaden such laws.
Where it stands: A House bill would allow federal courts to issue such orders in states without their own laws. Senators are considering a proposal that would offer grants as an incentive for more states to establish such laws.
What the analysis shows: Research has shown that awareness of the laws and enthusiasm for using them varies by jurisdiction. But there is some evidence they can prevent violence.
A study in Connecticut found that the presence of such a law reduced the number of gun suicides, which is the most common type of gun-related death. A study of red-flag applications in California from 2019 included several examples of people who had threatened mass violence.
In one case, a man who threatened to shoot his former co-workers after losing his job was flagged while he waited for a background check to clear on a shotgun. When police visited his home, they found 400 rounds of ammunition. Wintemute, a co-author on the study, said about 30% of red-flag applications in California had involved possible mass shooters.
“It critically depends on people being willing to obey the old adage: If you see something, say something,” he said. “There has to be a report. And that’s just the first step.”
In 57% of shootings, the attacker had issued a specific threat or was known to have been previously suicidal, behavior that might have initiated a gun confiscation. But in eight of those shootings, states had already enacted red-flag laws, an indication that threats of violence have not always resulted in gun confiscations, even when a law is on the books.
Banning So-Called Assault Weapons
Thirty percent of shootings involved guns that were banned under the now-expired 1994 federal assault weapons law.
The proposal: A House bill, not scheduled for a vote, would bar the sale of certain semi-automatic rifles, pistols and shotguns that the bill describes as assault weapons.
Where it stands: More than 200 House Democrats have co-sponsored the bill, but not enough to command a majority of the House. Rep. Jerry Nadler, D-N.Y., who is chair of the House Judiciary Committee, said he and colleagues were trying to persuade more lawmakers to support such a bill. An assault weapons ban seems unlikely to advance in the Senate. Some of the Republican senators who have been negotiating on other measures have opposed banning such a popular category of weapon.
What the analysis shows: Around 30% of the mass shootings in the database involved a weapon that would probably be banned by such a law. On average, they caused twice as many fatalities as other shootings.
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Methodology
There is no consensus on the definition of a mass shooting. The Violence Project follows the criteria used by the Congressional Research Service, which includes shootings in which four or more are killed excluding the attacker (attackers are not included in death totals). At least some of the murders must be in a public location and must not be “attributable to underlying criminal activity.” The database was last updated after the shooting in Buffalo. The Times added the more recent shooting in Uvalde, Texas.
The Times selected which criteria were relevant to each gun policy. Three shootings were excluded because they lacked data on the guns the attackers used, though they were factored into totals related to red flag laws. An additional one was excluded because the alleged assailants were acquitted and removed from the database. The data are counted by incident, not by shooter. (Three shootings in the period examined involved two attackers.)
Shootings were coded based on whether at least one attacker or one firearm that was used fit our criteria. For instance, if a shooting involved a combination of purchased and stolen guns, the shooting was coded as having involved stolen weapons.
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