Federal law barred Jody Lee Hunt from ever owning a gun. But when he wanted to buy one, it wasn’t hard: He found a seller on Facebook.
Mr. Hunt was a felon who had spent time in prison for abducting a girlfriend. But in December 2014, he used the handgun he found online to carry out a rampage in West Virginia, the authorities said, killing his ex-girlfriend, a rival business owner, and two others. In a note he wrote before turning the gun on himself, he said he wanted his victims to get “their fair pay of hurt.”
Millions of people in the United States are prohibited from owning firearms under federal law. They include felons like Mr. Hunt as well as fugitives, people adjudicated to be mentally ill, those dishonorably discharged from the military, and also convicted domestic abusers or others subject to domestic violence restraining orders.
They are supposed to be blocked by a federal instant background check database that licensed firearms dealers are required to query before handing weapons over to a buyer. This system has barred more than three million sales since it was enacted in 1993.
But federal gun laws contain a major loophole: Transactions between private sellers and buyers do not require a background check. That used to typically just mean sales at gun shows, or through listings found in classified ads. But that was before the internet made it as easy as a few mouse clicks to find a gun for sale from a private seller on an online marketplace or through social media.
The result: About one in five gun buys is conducted with no background check, according to Brady, a gun violence prevention group named for James Brady, Ronald Reagan’s press secretary, who was disabled by an assassination attempt against the former president.
“The advent of the internet has completely changed the game,” said Christian Heyne, Brady’s vice president of policy.
The loophole has remained in place despite polls showing high levels of public support for making all firearms sales subject to background checks. Gun-control activists see closing the loophole as the foundation for a comprehensive gun violence reduction plan, while the gun lobby, and many Republicans, have been vehemently opposed.
But in the wake of mass shootings that left 31 dead in El Paso and Dayton, Ohio, this month, President Trump and Republican leaders in Congress are facing new pressure to back measures to reduce gun violence. They have voiced support for expanding the background check system, though gun control activists are skeptical that they are committed to meaningful changes to the federal policy, particularly given Mr. Trump’s flip-flops on the issue.
About 20 states have their own comprehensive background check laws. Research has shown that these states see fewer guns used in crimes, but that the added state checks alone have not led to significant drops in gun-related deaths, said Daniel Webster, director of the Johns Hopkins Center for Gun Policy and Research.
Instead, state background check laws are more effective when they work in tandem with other measures requiring state or local permits to purchase weapons, which often include additional requirements for fingerprinting and handgun safety training. The combination, experts say, has reduced firearm homicides, suicides and shootings of law enforcement officers, as well as illegal gun trafficking.
Part of the reason may be that gun dealers, who have an incentive for sales to be approved, are a friendlier venue for some prospective buyers than getting a permit at the police station or sheriff’s office.
“If you’re someone with malicious intent, you may think twice about that gun if your first stop is a law enforcement agency,” Mr. Webster said.
But only so much can be gleaned from the experience of state background check laws because of the same problem that often befalls places with tighter gun laws: It is harder to force changes if nearby states have weaker regulations, which is one reason calls for universal background checks have been growing.
A stronger background check system most likely would not have prevented the massacres in Texas and Ohio, though other pending legislation, like a proposed assault weapons ban or new laws to temporarily take firearms away from people who appear to be dangerously unstable, could have had an effect.
But Mr. Hunt’s rampage in West Virginia, other killings and even some mass shootings might have been prevented by stronger background checks.
One perpetrator, Radcliffe Haughton, bought a handgun for $500 in the parking lot of a McDonald’s from a private seller he found on the internet, even though he was subject to a restraining order that made it illegal for him to own firearms. In 2012, he used the gun to open fire at a spa in suburban Milwaukee where his wife worked, killing her and two other women before he killed himself.
In 2016, Travis Spitler bought a handgun from a private seller even though he was also subject to a domestic protection order that should have prevented him from getting the weapon. He used the gun to kill his ex-girlfriend and wound two of her children at a Las Vegas day care center before killing himself.
Some gun sales involving licensed dealers have also shown why the federal background check system needs to be strengthened even more, gun violence prevention groups say.
A man who killed more than two dozen people at a Texas church in 2017 passed a background check at a licensed gun dealer because the Air Force failed to report to the federal background check database that he had been convicted at court-martial of domestic assault charges that should have barred him from gun ownership.
And the man who killed nine people at a Charleston, S.C., church in 2015 was able to buy his gun after a background check failed to immediately reveal that he had admitted possessing a controlled substance, which should have prevented the purchase. In what has since become known as the “Charleston loophole,” firearms dealers can hand over weapons to buyers if their background check has not been completed in three business days.
Some legislation now before Congress would significantly lengthen that window — which gun control advocates say would have given the authorities time to discover that the Charleston killer was prohibited from owning guns.
Some National Rifle Association officials have described universal checks as a first step toward large-scale gun licensing that would warp the Second Amendment into “a European-style privilege reserved for wealthy elite who can afford to comply with burdensome, bureaucratic procedures to acquire a firearm.”
They and other opponents also note that criminals overwhelmingly obtain guns that they use in their crimes not from licensed dealers or even unlicensed gun show sellers, but from sources like friends or the black market.
In turn, experts point out that universal background checks would help address the problem of sellers who supply criminals with weapons in these types of transactions, often doing so without having to fear prosecution in most states.
And there is also evidence that state background check laws can significantly influence online gun sales by discouraging private sellers from doing business with buyers without first completing the proper checks.
Everytown for Gun Safety, which favors tighter gun laws, made a striking discovery when it examined one major online firearms marketplace: More than 80 percent of unlicensed sellers on the site who were from states with background check laws said that they would require background checks before they would sell a weapon. But only 6 percent of sellers who were from states without similar laws said they would require the checks.
“Criminals know that the internet is the place to go to get armed with no questions asked,” the group concluded.