A US federal judge in Tacoma, Washington has put himself in a Catch 22: ruling a man charged with possessing child pornography has the right to review malware source code while also acknowledging that the government has a right to keep it secret.

"The resolution of Defendant’s Third Motion to Compel Discovery places this matter in an unusual position: the defendant has the right to review the full NIT code, but the government does not have to produce it," US District Judge Robert Bryan wrote on Wednesday. "Thus, we reach the question of sanctions: What should be done about it when, under these facts, the defense has a justifiable need for information in the hands of the government, but the government has a justifiable right not to turn the information over to the defense?"

In this case, the defense wants prosecutors to disclose the full source code of the NIT, or network investigative technique—a piece of government-created malware that compromised Tor and exposed users of a Tor-only child porn site. The Department of Justice did so in a related case in Nebraska, United States v. Cottom, but a DOJ spokesman now says this case, United States v. Michaud, and Cottom are entirely different cases and have no bearing on one another.

As Ars has reported previously, since defense lawyer Colin Fieman filed his third motion to compel discovery in January 2016, there have been two other judges overseeing related cases in different states that have ruled to suppress evidence found as a result of the NIT. Those cases, in Oklahoma and Massachusetts, have been significantly hindered as a result. (Earlier this month, a defense attorney in West Virginia filed a new motion to withdraw a guilty plea based on these other rulings.) These cases comprise a small handful in a group of 135 that have so far been prosecuted.

In early 2015, investigators used this NIT malware to penetrate the digital security of Tor users accused of accessing the Tor-hidden child pornography site called "Playpen." In yet another related case prosecuted out of New York, an FBI search warrant affidavit described both the types of child pornography available to Playpen’s 150,000 members and the malware’s capabilities.

You can’t have it both ways

Brian Owsley , a former federal judge who is now a law professor at the University of North Texas, said that such a conundrum is "not that uncommon." He pointed to a 1957 Supreme Court decision, Jencks v. United States, which involved an undercover informant and an alleged Communist who demanded government records from the investigation.

"The judge solves this problem by dismissing the charge against the defendant if the government does not want to release the code for the network investigative technique in this case based on an assertion of privilege," Owsley said by e-mail. "This enables the government to prioritize how important it is to maintain these documents. If the release truly would jeopardize national security or some other greater good as in this case, then the government must accept the dismissal of its prosecution of the one defendant for that greater good. So either the government will blink and allow the defendant access to the NIT code or the court may dismiss the indictment."

Ahmed Ghappour, a law professor at the University of California, Hastings, came to a similar conclusion. "The judge has already ruled that the source code is material to the defense, and the government has not made a sufficient showing that access to the source code cannot be used by the defense to mount a challenge," he wrote.

Judge Bryan is set to hold another hearing on this issue next week.