Prosecutors in the USA have dropped child pornography charges against a man because the FBI refused to reveal how it found out his identity.

The US Department of Justice (DOJ) said that it had dropped the case because the FBI did not want to reveal the Tor vulnerability it had used. According to the DOJ, several more cases could be affected.

Washington based Jay Michaud has been accused of downloading child pornography images from a site called ‘Playpen’, which was located on the Tor network. The Tor network allows internet users to anonymise their web traffic, and make it harder or next to impossible for Internet Service Providers (ISPs) and law enforcement agencies to identify what web sites the user has accessed. The Tor network does this by making use of a special web browser that hides people’s identities and locations by routing internet connections through a multitude of different computers and encrypts the data streams in the process.

Prosecutors in the USA have dropped child pornography charges against a man because the FBI refused to reveal how it found out his identity.

Washington based Jay Michaud has been accused of downloading child pornography images from the Playpan site.

The FBI actually ran the Playpen website for several weeks in 2015 after it clandestinely infiltrated the website in 2015, and then capitalising on its administrative privileges to use “network investigative techniques” so it could track down users and identify their real IP addresses, and thus their real identity and location.

But the FBI has refused a request to explain just how its “network investigative techniques” actually work, or the vulnerability in the Tor network it exploited in order to bring up the child pornography charges in the first place.

Federal prosecutor Annette Hayes wrote in a court filing, last Friday, that she was unwilling to take the case any further  “because the government remains unwilling to disclose certain discovery related to the FBI’s deployment of a ‘network investigative technique” thus depriving the DOJ “of the evidence needed to establish defendant Jay Michaud’s guilt beyond reasonable doubt.” She then went on to add that the US government had been forced to “choose between disclosure of classified information and dismissal of its indictment… disclosure is not currently an option.”

The Tor vulnerability in question has been used by the FBI to de-anonymize the real names and IP addresses of deep/dark web users and has so far been connected to around 200 prosecutions, all of which may now come under scrutiny and face a very real danger of having convictions dropped, and outstanding court cases stopped.