The Brady Center to Prevent Gun Violence said Wednesday it has filed a lawsuit against the Trump administration for failing to produce documents covered under a Freedom of Information Act request it submitted more than five months ago.

The center was seeking paperwork related to the U.S. State Department's decision in June to reverse course and allow 3D-printed gun blueprints to be published.

Dating back to the Obama administration, the department's previous position had been that publication would violate its control over firearms exports.

Texas resident Cody Wilson, who sells firearms parts online, had sued over the department's prohibition and in a settlement, the Trump administration allowed him to publish plans for 3D-printed guns.

"Citizens have the right to know why the State Department suddenly abandoned its winning position," Brady Center attorney Joshua Scharff said in a statement. "We do not know what the State Department is hiding, but we intend to find out."

A State Department spokesperson said via email Wednesday evening, "We would decline to comment on pending litigation."

The saga of 3D-printed guns was tumultuous in 2018, with federal judges twice attempting to block the release of Wilson's blueprints and Wilson selling them on his Defense Distributed website regardless.

In a case authorities said was unrelated, the 30-year-old Austin man was arrested and jailed in September after an underage girl alleged they had sex.

Meanwhile, the Brady Center argues that 3D-printed gun blueprints can make firearms hard to detect and trace because key components are essentially plastic, and users can produce them without serial numbers.

It said that the State Department has repeatedly argued such weapons are a "national security risk" but that it changed its tune for unknown reasons.

“You don’t forfeit a match after you’ve been winning," the Brady Center's Scharff told NBC News. "The public has a right to know why the State Department suddenly reversed course and put the security of the public in danger -- and we intend to find out."