President Donald Trump has signed a resolution blocking an Obama-era rule that would have prevented an estimated 75,000 people with mental disorders from buying guns.

The rule was part of former President Barack Obama's push to strengthen the federal background check system in the wake of the 2012 Newtown, Connecticut shooting.

In the shooting, 20-year-old Adam Lanza, who suffered from several mental impairments including Asperger’s syndrome and obsessive compulsive disorder, shot his mother dead at home, and then went to the school where he fatally shot 20 students between six and seven years old, as well as six teachers. He then turned the gun on himself. The massacre was the deadliest school shooting in US history, leaving 28 dead in total, and prompted President Obama to call for more stringent background checks and a ban on certain kinds of semi-automatic assault weapons.

It required the Social Security Administration to send in the names of beneficiaries with mental impairments who also need a third-party to manage their benefits.

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But lawmakers, the National Rifle Association and even the American Civil Liberties Union criticized the rule, saying it unfairly stigmatized the disabled and infringed on their constitutional right to bear arms.

Senator Charles Grassley, who pushed for the repeal, said the regulations are filled with “vague characteristics that do not fit into the federal mentally defective standard” for prohibiting someone from buying or owning a gun.