WASHINGTON -- The American Civil Liberties Union on Tuesday sued two former Air Force psychologists who designed a CIA program that used harsh interrogation techniques to elicit intelligence from suspected terrorists, saying the pair endorsed and taught torture tactics under the guise of science.

The lawsuit comes 10 months after the release of a damning Senate report that said the interrogation techniques had inflicted pain on al Qaeda prisoners far beyond the legal limits and did not yield lifesaving intelligence.

The suit accuses the psychologists, James E. Mitchell and John "Bruce" Jessen, of developing an interrogation program that relied on beatings, sleep deprivation, starvation, waterboarding and other methods that caused physical and psychological suffering on prisoners in CIA custody.

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A lawyer who has represented the pair did not immediately return messages seeking comment on Tuesday.

The suit was filed in federal court in Washington state on behalf of three former CIA prisoners. One, Gul Rahman, was interrogated in a dungeon-like Afghanistan prison called the Salt Pit, subjected to isolation, darkness and extreme cold water, and was later found dead of hypothermia. The other two men, Suleiman Abdullah Salim and Mohamed Ahmed Ben Soud, are now free.

The lawsuit was brought under the Alien Tort Statute, which allows noncitizens to sue in U.S. courts over human-rights violations. A 2010 Associated Press report, citing former U.S. officials, said the CIA had promised to cover at least $5 million in legal fees for the psychologists if the program ran into trouble.

"They claimed that their program was scientifically based, safe and proven, when in fact it was none of those things. The program was unlawful and its methods barbaric," Steven Watt, a senior staff attorney with the ACLU Human Rights Program, said in a statement.

The suit repeats many of the allegations that surfaced in an exhaustive Senate investigation issued last year. It found sweeping flaws with the CIA's approach to interrogations.

The complaint alleges that the psychologists, despite having no practical interrogation experience or specific background in al-Qaeda, devised a program for the CIA that drew from 1960s experiments involving dogs and the theory of "learned helplessness." In making their case to the CIA, the psychologists argued that just as abused dogs will ultimately become passive and compliant, humans subject to "uncontrollable pain" would "become helpless and unable to resist an interrogator's demand for information," according to the lawsuit.

The pair, who worked as independent contractors for the CIA, formed a company that was ultimately paid $81 million and which as of April 2007 directly employed 11 of the 13 interrogators used by the agency, the complaint states. The contract was ended in 2010.

The ACLU also says the men themselves were involved in some of the interrogations, including of Abu Zubaydah, a captured al-Qaeda operative who was waterboarded dozens of times in 2002.

The Justice Department approved the use of harsh interrogation methods proposed by the CIA in legal memos that were subsequently withdrawn and discredited.

Following release of the Senate report last year, Mitchell told The Associated Press that he could not confirm his involvement with the CIA because of a secrecy agreement. But he challenged the report's conclusion that the interrogation tactics did not produce otherwise unobtainable intelligence.

"I completely understand why the human rights organizations in the United States are upset by the Senate report," Mitchell said at the time. "I would be upset by it too, if it were true."

"What they are asking you to believe is that multiple directors of the CIA and analysts who made their living for years doing this lied to the federal government, or were too stupid to know that the intelligence they were getting wasn't useful."