The Senate nixed an Obama-era rule that could block some people receiving Social Security disability benefits from being able to buy a gun.
Senators voted 57-43 to strike down a regulation that requires the Social Security Administration to report people who receive disability benefits and have a mental health condition to the FBI's background check system.
The database is used to determine eligibility for buying a firearm.
The Senate's move will send the resolution of disapproval, which also passed the House last week, to President Trump's desk, where he is expected to sign it.
The rule was implemented by the Obama administration after the 2012 shooting at Sandy Hook Elementary School in Connecticut, where 20 children and six educators died.
Murphy, who represented Newtown, Conn., in the House, lambasted his GOP colleagues ahead of the vote, arguing they were making it easier for individuals with a mental illness to buy a gun.
"The [Congressional Review Act] we have before us today will make it harder for the federal government to do what we have told them to do for decades, which is to put dangerous people and people who are seriously mentally ill on the list of people who are prohibited from buying a gun," he said from the Senate floor.
He added that "we know that people with serious mental illness in this country can go buy a very powerful weapon and do great damage with it."
Republicans are moving quickly to dismantle Obama-era regulations using the Congressional Review Act.
The move allows them to bypass the Senate's higher 60-vote threshold, which would require the support of Democrats, and undo a rule with a simple majority in both the House and Senate.
Critics argue the rule stripped Second Amendment rights from people who are not dangerously mentally ill, such as those with eating or sleeping disorders or disabilities that prevent them from managing their own finances.
Majority Leader Mitch McConnellAddison (Mitch) Mitchell McConnellMcConnell: I'm going to give Biden's Supreme Court nominee 'a fair look' Progressive millionaire group backs Cisneros, McBath in first public endorsements Clyburn calls for full-court press on voting rights MORE (R-Ky.) noted that 20 disability groups have come out against the regulation.
"The reality is that, like us, they believe the regulation is simply bad policy, places an unfair stigma on those with disabilities and violates their constitutional rights which is why a wide array of groups oppose it," he said from the Senate floor.
The National Rifle Association also opposed the rule. The group said the determination of who is mentally ill should be left to courts.
The rule was set to go into effect in December. If the Social Security Administration reported an individual to the FBI's background check system, the person would be able to appeal the decision.
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