People on the national terrorism watch list are allowed to buy guns as long they don't have a criminal or mental health record, National Public Radio reports.
Some say it's a loophole that should be closed, while others argue that doing so would result in innocent people losing their constitutional right to buy guns.
Between 2004 and 2010, people on terrorism watch lists tried to buy guns and explosives more than 1,400 times. They succeeded in more than 90 percent of those cases, or 1,321 times, according to the Government Accountability Office.
"It's absurd that we allow people to buy unlimited AK-47s, AR-15s and Uzis, even if we feel they are too dangerous to be allowed on a plane, even after they've gone through a security check," Jon Lowy, a lawyer for the Brady Campaign, a gun control advocacy group, told NPR
A former White House counterterrorism official during the Bush administration points out that often times innocent people wind up on the list such as business associates, roommates or landlords of suspected terrorists.
Sen. Lindsey Graham of South Carolina agrees that's a problem.
"I think anyone who's on the terrorist watch list should not lose their Second Amendment right without the ability to challenge that determination," says Graham.
Since 2007, Sen. Frank Lautenberg of New Jersey has pushed for legislation that would close the terrorism watch list loophole. He would like to change the law so the U.S. attorney general would have discretion to block the gun sale for someone on the list. His most recent proposal was sent to a Senate committee in January and did not advance.