While federal law requires licensed gun dealers to run background checks on all prospective gun buyers, due to an NRA-backed loophole in the 1993 Brady Bill, gun sales can proceed by default after three business days—even without a completed background check.

Most background checks are completed on the spot, but typically 10 percent of all federal checks require additional time, with 3 percent of background checks are delayed longer than three days. A review of federal checks through the National Instant Background Check System (NICS) between 2014 and 2018 revealed that background checks delayed longer than three days are 4 times more likely to be denied.

This loophole presents a special danger for domestic violence victims. In its 2016 report, the Government Accountability Office found that background checks involving domestic violence flags take longer to resolve. Domestic violence prohibitions involve multiple criteria that often require significant investigation and coordination with local law enforcement. For example, because federal law only prohibits abusers from buying a firearm if they were married to their victims (or if they shared a child or a home), a background check may require investigation into the relationship between the parties. Between 2006 and 2015, it took the FBI more than three business days to determine 30 percent of denials based on misdemeanor crimes of domestic violence. That means licensed dealers were legally authorized under federal law to transfer guns to 18,000 people who were prohibited domestic violence misdemeanants simply because their background checks took longer than three days.