This is what is alleged to have happened to Binyam Mohamed, and the British courts expunged the reports, because of threats from US intelligence that they would stop cooperating with UK intelligence if the information were released, and the is arguing to continue the complete and absolute privilege that Bush and His Evil Minions^™ insisted upon:

“Is there anything material that has happened” that might have caused the Justice Department to shift its views, asked Judge Mary M. Schroeder, an appointee of President Jimmy Carter, coyly referring to the recent election.

“No, your honor,” Mr. Letter replied.

Judge Schroeder asked, “The change in administration has no bearing?”

Once more, he said, “No, Your Honor.” The position he was taking in court on behalf of the government had been “thoroughly vetted with the appropriate officials within the new administration,” and “these are the authorized positions,” he said.

(emphasis mine)

I Barack Obama decided that since he’s so awesome, we should just trust him.

We also have graphic depictions of what was done to the man (from the 2nd link):

The court papers describe horrific treatment in secret prisons. Mr. Mohamed claimed that during his detention in Morocco, “he was routinely beaten, suffering broken bones and, on occasion, loss of consciousness. His clothes were cut off with a scalpel and the same scalpel was then used to make incisions on his body, including his penis. A hot stinging liquid was then poured into open wounds on his penis where he had been cut. He was frequently threatened with rape, electrocution and death.”

(again, emphasis mine)

Note that the precedent here, US v. Reynolds, is in fact based on a lie. There were no state secrets involved, the B-29 which crashed was not, as was claimed, on a secret mission or testing secret equipment.

They claimed privilege because the report indicated that the aircraft was in poor condition because of inadequate maintenance, and the USAF wanted it covered up. It was all a lie.