It was called House Amendment 390, and it radically altered the implementation of the Brady background check bill. It was backed by the NRA. Twenty days later, it was the law. And 22 years later, one of its elements allowed Dylann Roof to get a gun.

Last week, Jim Clyburn, a Democratic Congressman from South Carolina, filed legislation that would close the so-called “default proceed loophole,” which allows federally licensed firearms dealers to proceed with a sale if a background check — as in Roof’s case — takes more than three business days to complete. Connecticut Sens. Chris Murphy and Richard Blumenthal echoed the call, urging President Obama to take executive action to extend the window that federal examiners have for making a determination on a purchaser.

“If law enforcement needs more than three days to ensure they’re not giving weapons to dangerous people, Washington must allow them the time to do their jobs,” Blumenthal and Murphy said in a statement.

House Amendment 390 is the part of the Brady Bill that sets the clock. Known colloquially as the Gekas amendment — for its sponsor, George Gekas, a House Republican from Pennsylvania and staunch NRA ally — it was introduced at the eleventh hour of a seven-year-long legislative fight. In the years since, the Gekas amendment has come to define the policy at the center of American gun violence–prevention efforts. Its primary purpose was to mandate the replacement of an interim, manual federal system for verifying prospective gun buyers’ eligibility with a national computer-based system capable of producing near-instant answers; the three business-day cutoff was an afterthought. But together those provisions have shaped the expectations for gun background checks, creating a bias toward speed.

For such a consequential piece of Congressional maneuvering, the backstory of the Gekas amendment is not widely known. Interviews on background with several key players in the creation of the legislation, along with a review of the Congressional record, paint a clear picture: In the waning days of the debate over the Brady bill, the NRA countered the inevitability of a rare defeat by trying to sink the bill from within — and instead wound up producing a federal background check system that differs in key ways from what its original champions envisioned.

First Draft: Seven Days to Get it Right

The first iteration of the Brady Handgun Violence Prevention Act called for a 50-state background check system with a seven-day investigation period for handgun sales. It was inspired by the shooting of President Reagan in 1981 and named after his press secretary, Jim Brady, who was paralyzed in the attack. (Brady ultimately died of those wounds in 2015. His death was ruled a homicide.) At the time of its passage, fewer than two dozen states, among them California and Massachusetts, had their own background check systems. The Brady bill would take background checks national.

A key component of the bill was the amount of time allotted for the government to complete a check on a prospective gun buyer. If the check was not completed in this time frame, the sale was allowed, by law, to be completed.

The Brady bill called for applications to be vetted by the local chief law enforcement officer, who would be empowered to block sales to dangerous persons. It also drew immense scrutiny from pro-gun lawmakers. In 1988, a version of the bill was presented in the House as an amendment to antidrug legislation, but it failed to pass. In 1990, Brady passed the House Judiciary Committee. But in what critics consider to be a favor to the NRA, Democratic Tom Foley of Washington state, the Speaker of the House and an opponent of gun restrictions, kept the bill from coming up for a full floor vote.

Thanks in part to a sustained NRA campaign to scuttle the law, including targeted ads aimed at key House reps, the bill became “one of the most contested issues in the country, dividing gun control supporters and opponents with a vehemence generally reserved for the most contentious social issues,” criminal justice consultant Richard Aborn has written. In 1991, the bill passed the House (with 42 more votes than the first time it came up for a vote) and the Senate — only to have the conference report fail a Senate cloture vote, stalling the legislation again.

But public support for reform was building; that spring, even Ronald Reagan, an NRA member, had voiced his support. By the time Bill Clinton was inaugurated in 1993, the Brady bill’s passage seemed increasingly likely.

That legislative momentum only heightened the wariness of gun owners with spotless criminal records, who feared getting tied up in bureaucratic red tape. Richard Feldman, now president of the Independent Firearms Owners Association, worked as an NRA lobbyist at the time. He orchestrated the early push against Brady before reversing course after leaving the organization. “A lot of gun sales are impulse buys,” as Feldman points out, and that instant gratification was jeopardized by visions of purchases held up for a week by a clearance system that was just going to determine the buyer was legit after all. It was in these understandable (if ultimately unfounded) concerns that opponents of the Brady bill saw a valuable opening.

The NRA Plays Its Trump Card

While pushing back against the Brady bill with attack ads and campaign donations, the NRA was also fighting on a second front, promoting killer amendments through its allies in Congress.

In the case of Brady, most of these involved floating an instant computerized background check system for which the technology did not yet exist. While a digitized records database seems simple enough to execute today, the architects of Brady had imagined local law enforcement sifting through boxes of paper to match names with criminal histories. At that time, an investigator could locate an arrest record belonging to a prospective buyer, but he or she needed to call the courthouse to see if it led to a conviction, because the disposition of most criminal charges was usually omitted. This is why the bill that moved through Congress allotted five business days for the check (down from the original seven). But as early as 1979, Sen. Bob Dole had floated the notion of a future when these records were centralized and summoned in real time. It was around that idea that opponents of longer investigation periods for gun purchases now rallied.

The political strategy behind the NRA’s killer amendments, Robert Spitzer writes in The Politics of Gun Control, “seemed to offer a meaningful reform yet posed no actual change in gun purchasing procedures for many years to come.” The bet was that the changes would never be achievable within the Congressionally prescribed timeline, and would take down the whole background check system when they proved infeasible.

A killer amendment calling for study of an instant check system helped squash Brady background checks in 1988, and in 1991 the bill moved forward in the House only after besting a competing measure proposed by Democrat Rep. Harley O. Staggers of West Virginia, who called for an instant check system to be up and running within an impossible six months.

Gekas’s 1993 amendment proved to be the most important embodiment of this approach, because it shaped a bill that actually passed. It required that a computerized system — referred to then as InstaCheck — be installed within five years of Brady’s enactment. It also drastically reduced the five-day investigation period, calling for 24 hours instead.

Since the NRA viewed the investigation period for Brady background checks as “arbitrarily selected,” they would expire — not when the technology was ready, but on a five-year timetable.

Gekas, striking a magnanimous note, theorized on the House floor that the creation of “a high-charged instant check system” should take no longer than that.

“In committee and in conversation among people interested in this issue, many of us felt that 30 months would have been enough,” Gekas said on the House floor. But the kind of technology Brady opponents described — something akin to a credit card point-of-sale terminal — wasn’t yet widely in use. At that point, the Internet largely consisted of Usenet newsgroups and file download servers, and NASA video conferenced at two frames per second.

Gekas’s NRA ties were not a secret. FactCheck.org would report in 2013 that an NRA spokesman was quoted in a press release saying that the group “worked closely with [Gekas] on the language and to round up support for it.”

His amendment was initially rejected, but when he tweaked it slightly and requested a floor vote on November 10, 1993, it passed the House 238 to 192, with 122 Republicans and 84 Democrats voting “aye.” The full Brady bill passed the House later that day. When the Senate took up the legislation, lawmakers were faced with Gekas’s one-business-day time limit, which would go into effect five years after Brady’s enactment, along with the instant check system. But after further maneuvering in the Senate, the investigation period was raised to three days.

On the night of November 20, 1993, the Brady Act passed the Senate 63 to 36, with 47 Democrats and 16 Republicans voting yes. President Bill Clinton signed it into law on November 30.

Charles Schumer, who shepherded the legislation in the House, would later testify about the “tortuous negotiations” necessary to get the Brady bill to Clinton’s desk. Though he called the instant check provision (which would come to be known as the National Instant Criminal Background System, or NICS) “unworkable,” he conceded that “it was a necessary compromise to pass the most important gun control legislation since 1968.”

Five days before the bill signing, Wayne LaPierre gave his own assessment of the outcome, reiterating his group’s stance: “The waiting period is unfair to honest, law-abiding people. The criminals won’t wait.” But in actuality, the group had triumphed. It managed to maintain political cover with supporters by fighting an unflinching war against the bill in the public arena while simultaneously watering it down from within. And more than ever before, it proved that it could mobilize its three-million-strong membership in the process.

Ten months before NICS was scheduled to go online, Clinton floated the idea of indefinitely extending the five-day investigation period used by the interim manual background check system. But the Republicans who had taken over control of Congress proved inhospitable to any further alterations.

The FBI Voices Concern

Few gun violence–prevention advocates who spoke to The Trace fully anticipated the loophole that default proceeds represented. But it did not take long for the FBI to notice it. The first evaluation of the instant check system revealed that a purchaser whose evaluation takes more than 24 hours to complete is nearly 20 times more likely to be a person prohibited by law from owning a gun because of their criminal history or other disqualifying factor. According to that report, of the 89,836 denials issued during the first year, more than a third would not have been stopped if Gekas’s proposed 24-hour limit had been in place.

A second NICS evaluation released the following year cautioned that, while default proceed transactions are a very small percentage of total transactions, “they are a cause for concern given the fact that their absolute number is large and they present risks to public safety.” Today, sales approved by federally licensed gun sellers after the three-business-day determination period are eight times more likely to involve a prohibited purchaser than sales with background checks that are resolved within 72 hours, according to a 2009 study by Mayors Against Illegal Guns. (Mayors Against Illegal Guns is an earlier iteration of Everytown for Gun Safety, a seed donor of The Trace.)

The FBI currently performs NICS checks in in 36 states. The rest rely their own systems (which tend to be more comprehensive) or a combination of both. The bureau says it runs 58,000 NICS checks on a typical day, which are handled by staffers at one of the NICS-contracted call centers. In 2014, the FBI reported that 2 percent of background checks end with the FBI failing to render a determination.

Mobilizing Against the Latest Loophole

Default proceeds are a problem, says Matt Bennett, who worked on gun policy in the Clinton White House and is now senior vice president for public affairs at Third Way. “But whether that problem leads directly to crime or not is largely unknown. In our view, there are way, way bigger problems, like that NICS doesn’t cover the Internet or gun shows.”

That gun show loophole came to national attention after the Columbine killers used it to straw purchase their weapons. The inadequacies in the reporting of mental health records to NICS came to light after the Virginia Tech shooter legally bought guns despite the fact that a judge had deemed him a danger to himself because of mental illness two years prior. The default proceed loophole, says Robert Spitzer, “is less a time-bomb and more a firecracker.”

But now the three-business-day rule does have lawmakers’ attention. The number of illegal guns that pass through this loophole might not match those that move through others. But when it does happen, a state senator and eight of his parishioners can perish in a hail of gunfire while studying the Bible at church on a Wednesday evening.

[Photo: AP Photo/Doug Mills]