Further Reading Judge says suspect has right to review code that FBI has right to keep secret dropped their appeal in United States v. Michaud.

The case is just one of 135 federal prosecutions nationwide involving the Tor-hidden child porn website Playpen. The vast effort to bust Playpen has raised significant questions about the ethics, oversight, capabilities, and limitations of the government’s ability to hack criminal suspects.

In United States v. Michaud, Jay Michaud of Vancouver, Washington allegedly logged on to Playpen in 2015. But unbeknownst to him at that point, federal investigators were temporarily operating the site for 13 days before shutting it down. As authorities controlled Playpen, the FBI deployed a sneaky piece of software (a "network investigative technique (NIT)," dubbed by many security experts as malware), which allowed them to reveal Playpen users’ true IP addresses. With that information in hand, identifying those suspects became trivial.

Since being apprehended, some of the Playpen defendants immediately took plea deals. Others have challenged the government's NIT and the single out-of-district warrant that authorized its use.

In this case, US District Judge Robert Bryan eventually ordered the government to hand over the NIT's source code. Since that May 2016 order, the government has classified the source code itself, thwarting efforts for criminal discovery in more than 100 Playpen-related cases that remain pending. In June 2016, prosecutors began the appeals process to the 9th US Circuit Court of Appeals, but they ultimately decided to abandon Michaud at the higher court.

Further Reading Judge rules in favor of child porn suspect: Search warrant was improper

Michaud’s federal public defender, Colin Fieman, has been dogged in trying to force the government to reveal more information about how the NIT worked.

“We’re not out of the woods yet because they can ask for another motion to reconsider,” Fieman told Ars. “It may not be a dismissal of the indictment at this point, but it would be odd for them to try to pursue further. But we’ll have to wait and see.”

Last year, a federal judge in a related case prosecuted out of Oklahoma, United States v. Arterbury, also ruled against the prosecution. The government eventually dropped the appeal and then dismissed the indictment at the district court in October 2016. Yet another Playpen case, United States v. Levin, where the defense prevailed initially, is currently on appeal at the 1st US Circuit Court of Appeals. Beau Croghan, a man in Iowa, was another alleged user hit by this NIT—his case was just one of three in which a judge ruled to suppress the evidence due to a defective warrant. Croghan's case is now pending before the 8th US Circuit Court of Appeals.

Beyond Michaud, Fieman is representing another Playpen defendant in the same judicial district (the Western District of Washington) before the very same judge. In the second case, the evidence and legal questions are nearly identical. That case, United States v. Tippens, is set to go to trial on February 27, 2017 in Tacoma.