The limited resources spent examining whether the interrogation measures worked were in stark contrast to the energy the CIA devoted to collecting memos declaring the program legal.
Justice Department memos released this month show that the CIA repeatedly sought new opinions on the legality of depriving prisoners of sleep for up to seven days, throwing them against walls, forcing them into tiny boxes and subjecting them to the simulated drowning technique known as waterboarding.
Whether those methods worked is facing independent scrutiny for the first time only now, three months after President Obama banned the CIA from using them.
As part of an executive order shutting down the CIA's secret prisons, the White House has set up a task force to examine the effectiveness of various interrogation approaches.
The Senate Intelligence Committee launched a similar review, and began combing through classified CIA cables that describe daily developments in the agency's interrogations of prisoners suspected of ties to Al Qaeda.
"To the best of our knowledge, such a review has not been done before," said a Senate aide involved in the investigation.
CIA spokesman Paul Gimigliano declined to comment on the reviews, saying their contents remained classified.
A U.S. intelligence official who defended CIA interrogation practices said that "productivity was an obvious and important measure of the program's effectiveness. The techniques themselves were not designed to elicit specific pieces of information, but to condition hardened terrorists to answer questions about Al Qaeda's plans and intentions.
"By that yardstick -- the generation of reporting that was true and useful, that led even to other captures -- it worked," the official said.
Obama has described the agency's activities as "a dark and painful chapter in our history," and senior members of his administration, including Atty. Gen. Eric H. Holder Jr., have called the techniques torture.
Defenders of the program, including former Vice President Dick Cheney, have accused Obama of dismantling a capability that was crucial to keeping the country safe. Cheney also has called for the release of classified documents that he said would show how effective the program was.
Officials said that Cheney was probably referring to memos drafted by leaders of the CIA's counter-terrorism center to serve as talking points on the program to use in briefings for members of Congress and White House officials.
