Perhaps the clearest public CIA statement was a May 2011 letter from then-Director Leon Panetta to Sen. John McCain about whether "enhanced interrogation techniques" had provided leads that identified Osama bin Laden's hiding place. "Whether those techniques were the 'only timely and effective way' to obtain such information is a matter of debate and cannot be established definitively," he wrote.

This ambiguity wasn't acceptable to Feinstein. When the movie "Zero Dark Thirty" appeared in December 2012 (the month her committee finished the report) suggesting that harsh interrogation had, indeed, generated leads that led to bin Laden's hideout, she co-authored a letter that blasted the movie for even considering the possibility. "The use of torture should be banished from serious public discourse," the letter argued, in what sounded almost like an attempt to censor debate.

After Brennan became CIA director in 2013, the battle lines hardened further. Like Feinstein, he was obdurate on what he considered matters of principle. President Obama had privately cautioned Brennan in May 2013 that he didn't want him to defend the interrogation program. But when the director this past January learned that Senate investigators had obtained, copied and removed from a CIA facility a sensitive, off-limits document known as the "Panetta review," he went ballistic. The initial mistake here was probably the CIA's, for inadvertently putting the document - an unofficial draft by mid-level CIA staffers - in a computer system where Senate investigators could grab it. But the war was on.

The CIA's Office of Security rashly searched the Senate staff's computers at a CIA facility - triggering an investigation by the agency's inspector general. Whereupon, the CIA general counsel imprudently sent a "crimes report" to the Justice Department requesting an investigation of how the Senate staffers had obtained the Panetta document.

It was a royal mess, and the opposite of how oversight is supposed to work. Brennan shouldn't have waged this fight: The CIA never really wins when it battles Congress. But Feinstein should recognize that the reason to oppose torture is because it's immoral - not because a prosecutorial, 6,300-page Senate report claims that it never works.

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