THE ACLU SUED the Federal Bureau of Prisons (BOP) on Thursday for documents related to its inspection of a CIA black site in 2002. According to the executive summary of the Senate Intelligence Committee’s torture report, which was declassified in 2014, officers from the BOP conducted a detailed assessment of the infamous detention center known as “COBALT,” or the “salt pit,” near Bagram Airfield in Afghanistan.

After the ACLU filed a request for those documents in 2014, the bureau twice denied having any. Under the Freedom of Information Act, the government cannot deny the existence of documents it holds outright; instead, the government must notify the requester that it is withholding documents, and reference specific “exemptions,” like national security.

The ACLU lawsuit alleges that either the bureau conducted an inadequate search, or is illegally denying the existence of documents.

According to the summary of the torture report, the CIA consulted the Bureau of Prisons in 2002 because of its “lack of experience running detention facilities” and its need for people with “specialized expertise to assist the CIA in operating the facilities.”

According to the report, several BOP officers toured COBALT in November 2002 and conducted a detailed assessment. CIA interrogators quoted in the Senate report described the facility as “a dungeon,” where detainees “cowered” as interrogators opened the door and “looked like a dog that had been kenneled.”

Some of the CIA’s worst abuses happened at COBALT, including rectal exams that were conducted with “excessive force.”

Even as the BOP officers toured the facility, one CIA detainee was tortured to death. After being dragged outside his cell, stripped naked, beaten, and immersed in cold water, Gul Rahman was put in an isolation cell overnight, where he died of hypothermia.

According to a CIA officer who was quoted but not named in the Senate report, BOP personnel were “WOW’ed” by the prison, having “never been in a facility where individuals are so sensory deprived” with “everyone in the dark.”

Despite observing that “there is nothing like this in the Federal Bureau of Prisons,” the inspectors concluded that the “salt pit” was “sanitary” and “not inhumane,” and that the CIA “did not mistreat the detainees.”

ACLU lawyers argue that their lawsuit is essential to determine not only the role the BOP played in the CIA’s torture program, but also to reveal how the BOP understands prisoner abuse.

“The Federal Bureau of Prisons not only runs the federal prison system, but also provides technical assistance to prison officials around the country,” said Carl Takei, a staff attorney with the ACLU’s National Prison Project, in a statement emailed to The Intercept. “If the Bureau of Prisons is willing to certify that a dungeon like COBALT is ‘not inhumane,’ then why should anyone trust the bureau’s assurances that its own prisons are humane?”