Last Thursday, the Brady Center to Prevent Gun Violence stepped into a notable legal battle between Defense Distributed , a group that promotes gunsmithery via 3D printing, and the State Department, which aims to halt re-publication of the relevant CAD files.

The Brady Center is arguing in favor of the government, while the Electronic Frontier Foundation is on the side of Defense Distributed. The lawsuit, Defense Distributed v. Department of State, centers on whether a website that publishes CAD files—which would enable foreigners outside the US to print a firearm—violates munitions export laws. While Defense Distributed took the files down three years ago, they have since reappeared on BitTorrent sites. The case remains pending in the 5th Circuit Court of Appeals in New Orleans, which has yet to schedule oral arguments.

"Not only is Appellants’ position reckless and hazardous to the safety of Americans at home and abroad, it is inconsistent with the U.S. Constitution," John D. Kimball, the Brady Center’s attorney, wrote in the new amicus brief. "The Second Amendment does not protect the export of firearms or their functional equivalent."

The federal civil suit originated three years ago when Cody Wilson and his group, Defense Distributed, published designs for the " Liberator ," the world’s first 3D-printed handgun.

Within months, Defense Distributed received a letter from the United States Department of State’s Office of Defense Trade Controls Compliance, stating that 10 files, including the designs of the Liberator, were in violation of the International Traffic in Arms Regulations (ITAR). This is despite the fact that these files had already been downloaded hundreds of thousands of times and continue to circulate online.

Defense Distributed removed the files for fear of criminal and civil liability. The group then re-submitted a "commodity jurisdiction request" to the Department of State, which they hoped would clear the way for the publication of the files. After waiting for two years, Defense Distributed, along with the Second Amendment Foundation, sued the Department of State and argued that the government’s action constituted "prior restraint"—preventing publication before it occurs. In the United States, the Supreme Court has generally rejected the concept of prior restraint.

In 2015, as that case moved forward, Defense Distributed and the Second Amendment Foundation lost a motion for a preliminary injunction, which they appealed up to the 5th Circuit.

When public domain means something different

Curiously, the case seems to turn on whether the files in question are available to people outside the United States.

As the State Department wrote in its own filing from earlier this month:

So far as the State Department is concerned, Defense Distributed may transfer such files, including by making the files available for U.S. citizens to download on the Internet. This may be accomplished by verifying the citizenship status of those interested in the files, or by any other means adequate to ensure that the files are not disseminated to foreign nationals.

And that declaration, according to Wilson, is nearly tantamount to a victory for his side.

"The government is almost giving away the farm in what you’re recognizing to be admissions that maybe we could post the files on a semi-restricted website," he told Ars, adding that he had spent "half a million dollars" on this lawsuit.

Strangely, the case also relies on what is and isn’t considered "public domain," a concept that, despite the same wording, is wholly different from "public domain" in the world of intellectual property. Under ITAR, something that is "public domain" is merely something that is "generally accessible or available to the public."

However, because ITAR was written in the 1970s, it doesn’t explicitly recognize the Internet as a place that information can be "generally accessible."

"What about stuff that [the State Department] clearly doesn’t want but is already out there?" Robert Clifton Burns, an export lawyer who is not affiliated with this case, told Ars.

"In [State’s] newly proposed rules, they’re trying to say that it’s not in the public domain if the person didn’t have authorization from the government to put it on the Internet," he said. "But once folks have this, and it’s broadly distributed—leaving aside the idea of checking citizenship over the Internet—[the law] is written like somebody from 1920 was transported to the 21st century and for the first time is confronting technologies like 3D printers."

Defense Distributed also complicates things because it, unlike nearly every other corporation or government entity that would be affected by ITAR, is an organization that by definition wants to release its information as widely as possible.

"My whole goal in starting this company—this is the pathway to defeating a certain idea of technical control," Wilson added. "That without [Department of Defense] money we develop files and give up our claim on it, we would convey it to the commons, and it couldn’t be interdicted. Corporations couldn’t claim it and the government couldn’t claim it."

And that may be precisely what the government is most afraid of, said Burns. "I think in the end they’re looking at whacking Defense Distributed with a big fine, and this is the pre-game to that."

State Department lawyers did not respond to Ars’ request for comment.