US Attorney General Jeff Sessions has announced that people who make plastic firearms that are "undetectable" would be "prosecuted to the fullest extent of the law."
The statement comes a day after the US Justice Department asked a court not to block the public from downloading blueprints for the guns.
In 2015, Defense Distributed — an organization dedicated to creating downloadable materials for printing 3D guns — filed a lawsuit against the US federal government after the State Department, citing international arms control regulations, forced the removal of its instruction manuals from the Internet. In June 2018, the federal government settled the case, and the company said it would upload materials for 3D-printed guns to the internet beginning on August 1.
US President Donald Trump tweeted shortly before the TRO was issued that he was in talks with the National Rifle Association (NRA) and looking into sales of gun blueprints online, which, according to the president, did not "seem to make sense."
Following the ruling by a federal judge, a coalition of US gun rights activists called Code Is Free Speech began posting schematics for 3D-printed guns online, directly disobeying the court's decision.