John C. Kiriakou, who helped lead the team that caught the Qaeda operative Abu Zubaydah in Pakistan in March 2002, went public on ABC News this week with such a message. He said he saw intelligence reports saying that waterboarding, a technique that induces a sense of suffocation, had caused Abu Zubaydah to start talking after 35 seconds.

But Mr. Kiriakou, a 43-year-old father of four who left the agency in 2004, also said in an interview that he believed waterboarding was torture and should never be used again, because “we Americans are better than that.” He added: “I think the second-guessing of 2002 decisions is unfair. What I think is fair is having a national debate over whether we should be waterboarding.”

Legal hazards were on the minds of Bush administration officials from the beginning of the response to 9/11. The 2002 Justice Department interrogation opinion laid out some defenses interrogators might use against criminal accusations of torture.

“The administration’s success in preventing attacks has become its enemy,” said John Yoo, the former Justice official who wrote most of the 2002 opinion. Since then, he added, “The political environment has changed because people feel the threat is less than it used to be.”

Mr. Yoo’s legal opinions, though criticized as seriously flawed by some scholars, may nonetheless provide impenetrable armor for C.I.A. officers. From the beginning, wary agency officials insisted on what they called “top cover”  written Justice Department approval for what they did.

Most legal scholars say that even under a future administration, the Justice Department would not seek charges against C.I.A. officers for actions the department itself had approved.

Another obstacle to such prosecutions would be the laws passed by Congress in 2005 and 2006 granting extensive legal protection for authorized conduct. But the videotape destruction may not have such protection; the episode recalls the adage of Washington scandals  that it’s not the crime, it’s the cover-up that leads to trouble.