Bybee’s memo was aimed at one particular detainee, Abu Zubaydah, who had been captured some four months earlier, in late March 2002. Zubaydah is portrayed in the memo (as he was publicly by Bush after his capture) as one of the top men in Al Qaeda. But by August this had been proven false. As Ron Suskind reported in his book “The One Percent Doctrine,” Zubaydah was identified soon after his capture as a logistics guy, who, in the words of the F.B.I.’s top-ranking Qaeda analyst at the time, Dan Coleman, served as the terrorist group’s flight booker and “greeter,” like “Joe Louis in the lobby of Caesar’s Palace.” Zubaydah “knew very little about real operations, or strategy.” He showed clinical symptoms of schizophrenia.

By the time Bybee wrote his memo, Zubaydah had been questioned by the F.B.I. and C.I.A. for months and had given what limited information he had. His most valuable contribution was to finger Khalid Shaikh Mohammed as the 9/11 mastermind. But, as Jane Mayer wrote in her book “The Dark Side,” even that contribution may have been old news: according to the 9/11 commission, the C.I.A. had already learned about Mohammed during the summer of 2001. In any event, as one of Zubaydah’s own F.B.I. questioners, Ali Soufan, wrote in a Times Op-Ed article last Thursday, traditional interrogation methods had worked. Yet Bybee’s memo purported that an “increased pressure phase” was required to force Zubaydah to talk.

As soon as Bybee gave the green light, torture followed: Zubaydah was waterboarded at least 83 times in August 2002, according to another of the newly released memos. Unsurprisingly, it appears that no significant intelligence was gained by torturing this mentally ill Qaeda functionary. So why the overkill? Bybee’s memo invoked a ticking time bomb: “There is currently a level of ‘chatter’ equal to that which preceded the September 11 attacks.”

We don’t know if there was such unusual “chatter” then, but it’s unlikely Zubaydah could have added information if there were. Perhaps some new facts may yet emerge if Dick Cheney succeeds in his unexpected and welcome crusade to declassify documents that he says will exonerate administration interrogation policies. Meanwhile, we do have evidence for an alternative explanation of what motivated Bybee to write his memo that August, thanks to the comprehensive Senate Armed Services Committee report on detainees released last week.

The report found that Maj. Paul Burney, a United States Army psychiatrist assigned to interrogations in Guantánamo Bay that summer of 2002, told Army investigators of another White House imperative: “A large part of the time we were focused on trying to establish a link between Al Qaeda and Iraq and we were not being successful.” As higher-ups got more “frustrated” at the inability to prove this connection, the major said, “there was more and more pressure to resort to measures” that might produce that intelligence.

Image Frank Rich Credit... Fred R. Conrad/The New York Times

In other words, the ticking time bomb was not another potential Qaeda attack on America but the Bush administration’s ticking timetable for selling a war in Iraq; it wanted to pressure Congress to pass a war resolution before the 2002 midterm elections. Bybee’s memo was written the week after the then-secret (and subsequently leaked) “Downing Street memo,” in which the head of British intelligence informed Tony Blair that the Bush White House was so determined to go to war in Iraq that “the intelligence and facts were being fixed around the policy.” A month after Bybee’s memo, on Sept. 8, 2002, Cheney would make his infamous appearance on “Meet the Press,” hyping both Saddam’s W.M.D.s and the “number of contacts over the years” between Al Qaeda and Iraq. If only 9/11 could somehow be pinned on Iraq, the case for war would be a slamdunk.