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As Ars has reported, federal investigators temporarily seized a Tor-hidden site known as Playpen in 2015 and operated it for 13 days before shutting it down. The agency then used a “network investigative technique” (NIT) as a way to ensnare site users.

However, according to newly unsealed documents recently obtained by the American Civil Liberties Union, the FBI not only temporarily took over one Tor-hidden child pornography website in order to investigate it, the organization was in fact authorized to run a total of 23 other such websites.

According to an FBI affidavit among the unsealed documents: