According to FBI affidavits obtained by the American Civil Liberties Union, the FBI seized and ran 23 different Tor-hidden child porn sites. During their operations of the site, the FBI used a “network investigative technique” (NIT) in order to catch users who trafficked the porn sites.
The affidavit states that these sites were run from "government facilities."
In the normal course of the operation of a web site, a user sends "request data" to the web site in order to access that site. While Websites 1-23 operate at a government facility, such request data associated with a user's actions on Websites 1-23 will be collected. That data collection is not a function of the NIT. Such request data can be paired with data collected by the NIT, however, in order to attempt to identify a particular user and to determine that particular user's actions on Websites 1-23.
According to ARS Technica, the FBI was able to arrest over 200 child porn suspects through the use of the NIT malware program. However, some federal judges hold that this kind of snare violates the law.
Of the more than 100 Playpen-related child pornography cases that have been prosecuted, federal judges in Iowa, Massachusetts, and Oklahoma have ruled that such a search violated current laws of federal procedure and was in fact so egregious that the evidence collected as a result should be tossed. Other judges have rebuked prosecutors for unlawful searches, but they have not gone so far as to suppress evidence.
While some legal experts argue that the FBI was not necessarily running them, the affidavit asserts that the sites were at least "hosted at a government facility, with the FBI's knowledge and to the FBI's informational benefit."