The film's unflinching portrayal of the Central Intelligence Agency's brutal interrogation of Al Qaeda prisoners hews close to the official record, offering a gruesome sampling of methods like the near-drowning of waterboarding.
What has already divided the critics, journalists and activists who have watched early screenings is a more subtle issue: The suggestion that the calculated infliction of pain and fear, graphically shown in the first 45 minutes of the film, may have produced useful early clues in the quest to find the terrorist leader, who was killed in May 2011.
Such a claim is anathema to outspoken critics of the Bush administration's decision in 2002 to resort to methods that the United States had for decades shunned as illegal. And a new, 6,000-page report on CIA interrogations by the Senate Intelligence Committee, based on a study of some 6 million pages of agency documents, concludes that brutal treatment was not "a central component" in finding bin Laden, according to the committee's chairwoman, Sen. Dianne Feinstein, D-Calif.
But the report, which the committee will decide whether to approve on Thursday, remains classified, with little likelihood that any of it will be public for months. It has already become fodder for a partisan fight, with Republicans denouncing it as flawed and incomplete.
Nearly a decade after the CIA is last known to have waterboarded a suspect, the U.S. argument over torture remains unresolved and has lost little of its emotional potency, whether the spark is a blockbuster movie or a Senate report.
According to intelligence officials and the incomplete public record, detainees who endured varying degrees of physical force did tell their interrogators some truths, as well as half-truths and outright lies. What remains unprovable is whether - as FBI agents with long experience questioning terrorists have argued - the same or better information might have been obtained without taking the morally and politically treacherous path the CIA chose.
Mark Boal, the screenwriter of "Zero Dark Thirty," which is directed by Kathryn Bigelow, said in an interview Wednesday that the movie was no documentary, though it is based on extensive research.
"I'm trying to compress a program that lasted for years into a few short scenes," he said. The film, he said, attempts "to reflect a very complex debate about torture that is still going on" and shows brutal treatment producing both true and false information.
Jameel Jaffer, deputy legal director of the American Civil Liberties Union, who saw the film Tuesday night, said he was concerned that because the film opens with torture and ends with the killing of bin Laden, "it may leave a hazy impression that it was cause and effect."
But he added: "I don't think it makes a strong case for or against torture. It shows the big breaks came from good, old-fashioned intelligence work."
A major difficulty in judging just how faithful "Zero Dark Thirty" is to the facts is that many facts remain hidden from the public.
Though President Barack Obama has repeatedly condemned such methods - his only appearance in the film is on a television that shows him declaring, "America doesn't torture" - he also declared on taking office that he preferred to "look forward, not back," and there has never been a public official inquiry into torture and the questions that surround it such as its effectiveness, its legal basis and how extensively it was used.
Feinstein calls her committee's report "comprehensive" and "strictly factual." In previous public comments, she made clear that the report is harshly critical of the program, saying that the inquiry found that "coercive and abusive treatment of detainees was far more widespread and systematic than we thought."
But the report was written by Democratic staff members after Republicans declined to participate, and Sen. Saxby Chambliss of Georgia, the committee's top Republican, said the draft contained "significant errors and omissions," in part because it is based exclusively on documents rather than interviews. He said the draft should be given to the CIA for fact-checking before any committee vote.
"I do not understand why any member would vote for this report before that step is taken," he said.
The political divisions over the program have broken down largely along party lines - with the notable exception of Sen. John McCain, R-Ariz., who was tortured as a prisoner in North Vietnam, and who told reporters on Tuesday that the Senate report "absolutely" should be made public. Some 26 former senior military officers also urged the committee on Wednesday to approve and release the report.
But with even a partial declassification unlikely before next spring, "Zero Dark Thirty," to be released in New York on Dec. 19 and nationally on Jan. 11, may powerfully shape public impressions of the CIA program.
The extended interrogation scene shows a terrorist identified as Ammar, whom Boal describes as a composite character, being waterboarded, deprived of sleep, chained to the ceiling and forced into a small box. But he delivers his important nugget of information - that bin Laden used a courier known as Abu Ahmed al-Kuwaiti - only later, over a relaxed meal of hummus, after CIA officers trick him into believing that he has already spoken freely during torture sessions.
Another character, loosely based on a militant named Hassan Ghul, does speak candidly after saying he had been tortured by a Middle Eastern spy service and "I don't want to be tortured again." But in another scene, an Al Qaeda member called Abu Faraj al-Libi is shown - accurately, intelligence officials say - lying about the courier despite the brutal treatment he has experienced.
Most of the movie, however, portrays years of dogged intelligence sleuthing with no connection to torture. In the film, as in reality, the real breakthrough comes when the CIA learns the true name of the courier from a foreign intelligence service. "Zero Dark Thirty" portrays the name as having been overlooked for years in U.S. files; an intelligence official on Wednesday declined to say whether that is accurate.
The portrayal of torture in television shows like "24" - which makes no pretense of reflecting real events - may already have contributed to a notable shift in U.S. public opinion toward the idea that brutal interrogations are necessary and effective, said Amy B. Zegart, who studies intelligence at Stanford University.
She commissioned a poll in August that showed a switch since 2005 in views on the torture of terrorists who might know about new plots. There was a decline, for instance, in disapproval of waterboarding to 55 percent from 82 percent, and of chaining naked prisoners in uncomfortable positions in the cold to 51 percent from 79 percent. The more spy shows people have watched, she said, the more enthusiastic they are about torture.
"I think the evidence is that television is shifting views," said Zegart. "Entertainment has an alarming impact."