On Thursday, North Carolina, Pennsylvania, Virginia, and 17 other states filed a federal lawsuit to block the release of data files that show how to manufacture a firearm using a 3-D printer.

Attorneys general in 20 states and Washington, D.C., filed a lawsuit this week to prevent the Trump administration from allowing a company to release blueprints online that detail how to print a plastic gun from a 3-D printer.

“These 3-D firearm blueprints are just as dangerous now as they were when I first sued to prevent them from becoming publicly available online,” North Carolina Attorney General Josh Stein said in a statement released Friday. “Letting anyone have access to these files, and thus the ability to create undetectable, untraceable guns to hurt others, is a major threat to public safety. I will continue to fight to prevent the federal government from making these blueprints available to anyone and everyone.”

In 2018, Stein joined another multi-state lawsuit that aimed to block the Trump administration from allowing the Texas company Defense Distributed to post instruction manuals related to manufacturing a gun called the Liberator using a 3-D printer. A judge later ruled in their favor.

On Thursday, however, the Trump administration moved jurisdiction of certain firearms sales from the State Department to the Commerce Department in order to streamline the process for the export of firearms that do not have “an inherently military function,” an official told CNBC. The rule change will go into effect in March. 

“We condemn this move in the strongest possible terms,” Kris Brown, president of the Brady Campaign, said in a statement. “This is a naked show of support for the gun industry and yet another action taken by this administration in lockstep with one of their largest funders.”

According to the lawsuit filed in U.S. District Court in Seattle on Thursday, the state attorneys general argue the government’s actions are unlawful and that such deregulation will “make it far easier for individuals ineligible to possess firearms under state or federal law to obtain a deadly weapon without undergoing a background check.” 

3D-printed firearms, they argue, “are functional weapons that are often undetectable by standard metal detectors because they are made out of material other than metal (e.g., plastic) and untraceable because they contain no serial numbers.”

The concern, the complaint continues, is that anyone, including “violent felons, the mentally ill, and persons subject to protection and no-contact orders,” could easily manufacture and possess a weapon if they have access to such files. 

A majority of Americans support background checks for all gun owners, which would be impossible to implement for those who are capable of printing their own weapons.

The other states in the lawsuit are Washington, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Massachusetts, Maryland, Maine, Michigan, Minnesota, New Jersey, New York, Oregon, Pennsylvania, Rhode Island, Virginia, and Vermont.