The DoJ was forced to drop its indictment against Jay Michaud, a school administrator from Vancouver, Washington, when a federal judge asked that the agency disclose how it hacked the child porn site Playpen.

"The government must now choose between disclosure of classified information and dismissal of its indictment," the DOJ said in a court filing Friday. "Disclosure is not currently an option."

Michaud's case was just one of 137 indictments that the DoJ has brought against child porn viewers after the FBI seized the website in 2015. Instead of shutting it down, the FBI choose to keep it active for 13 days while it gathered the true IP address of the pedophiles.

It's unclear how the FBI managed to deploy malware on computers that visited Playpen, but it is speculated that it used an as yet unpatched flaw in the FireFox browser. The FBI refers to the exploit as a Network Investigative Technique (NIT) and has refused to disclose details about it claiming that it's classified.

Mozilla has filed a brief in court to have the FBI disclose its methods so the browser can be patched.

"The suppression order entered by the Court in May 2016 has deprived the government of the evidence needed to establish Defendant Jay Michaud’s guilt beyond a reasonable doubt at Trial," the DOJ said in its latest motion to dismiss the indictment. "Because the government remains unwilling to disclose certain discovery related to the FBI’s deployment of a 'Network Investigative Technique' ('NIT') as part of its investigation into the Playpen child pornography site, the government has no choice but to seek dismissal of the indictment."

The DoJ is seeking dismissal of the charges with prejudice so that, if the method is later disclosed, it can refile the charges.

Source: Network World