The result sets the stage for what could be the fullest public accounting of the Bush administration's record when it comes to waterboarding and other "enhanced interrogation techniques." The panel voted 11-3 to order the declassification of almost 500 pages of the 6,300-page review, which concludes the harsh methods employed at CIA-run prisons overseas were excessively cruel and ineffective in producing valuable intelligence.
Even some Republicans who agree with the spy agency that the findings are inaccurate voted in favor of declassification, saying it was important for the country to move on.
"The purpose of this review was to uncover the facts behind the secret program and the results, I think, were shocking," Sen. Dianne Feinstein, D-Calif., the committee chairwoman, said. "The report exposes brutality that stands in sharp contrast to our values as a nation. It chronicles a stain on our history that must never be allowed to happen again. This is not what Americans do."
The intelligence committee and the CIA are embroiled in a bitter dispute related to the three-year study. Senators accuse the agency of spying on their investigation and deleting files. The CIA says Senate staffers illegally accessed information. The Justice Department is reviewing competing criminal referrals.
As a result of Thursday's vote, the CIA will start scanning the report's contents for any passages that could compromise national security. That has led to fears in the committee that a recalcitrant CIA might sanitize key elements of their investigation, and demands for President Barack Obama to ensure large parts of the report aren't blacked out.
Obama, said Sen. Mark Udall, D-Colo., should "hold onto the redaction pen himself."
White House press secretary Jay Carney on Thursday restated Obama's support for declassifying the document and said intelligence officials would be instructed to conduct the work quickly. CIA spokesman Dean Boyd said his agency would "carry out the review expeditiously," but suggested the process may be difficult.
"We owe it to the men and women directed to carry out this program to try and ensure that any historical account of it is accurate," Boyd said.
The report was produced exclusively by Democratic staffers. It concludes among other things that waterboarding and other harsh techniques provided no key evidence in the hunt for Osama bin Laden, according to congressional aides and outside experts familiar with the document.
Feinstein and other senators also have cited a series of misleading claims by the CIA over the years about the effectiveness of the program, including in statements the agency made to President George W. Bush and Congress.
Sen. Saxby Chambliss of Georgia, the intelligence committee's top Republican, joined the vote in favor of declassification despite criticizing the report as a "waste of time." He said the U.S. public should be able to see the report alongside reservations among the GOP members of the committee.
"This is a chapter in our past that should have already been closed," Chambliss told reporters. He said Republicans would dispute some of the conclusions in their own report and insisted the CIA interrogations "led not only to the takedown of bin Laden, but to the interruption and disruption of other terrorist plots over a period of years."
Members of the intelligence community have criticized the investigation for failing to include interviews from top spy agency officials who authorized or supervised the brutal interrogations. They questioned how the review could be fair or complete.
"Neither I or anyone else at the agency who had knowledge was interviewed," said Jose Rodriguez, the CIA's chief clandestine officer in the mid-2000s, who had operational oversight over the detention and interrogation program. "They don't want to hear anyone else's narrative," he said of the Senate investigation. "It's an attempt to rewrite history."
Rodriguez himself is a key figure in the Senate report, not least for his order in 2005 to destroy 92 videotapes showing waterboarding of terror suspects and other harsh techniques.
Senate investigators were unable to talk to relevant CIA officials because of legal constraints posed by a separate investigation ordered by Attorney General Eric Holder. At Holder's direction, John Durham, an independent prosecutor, conducted several criminal probes related to interrogation methods and evidence destruction before dropping them altogether in 2012 - shortly before the Senate panel wrapped up its work.
Congressional aides said the CIA's own field reports, internal correspondence, cables and other documents described day-to-day handling of interrogations and the decision-making and actions of Rodriguez and others.
Republican Sens. Marco Rubio of Florida, Dan Coats of Indiana and Jim Risch of Idaho voted against releasing the report.
"Too much time, energy and too many resources have been spent investigating a CIA program that ended more than six years ago," Coats said.
Bad blood between Senate aides and the CIA ruptured into the open last month when Feinstein took to the Senate floor to accuse the agency of improperly monitoring the computer use of Senate staffers and deleting files, undermining the Constitution's separation of powers.
Thus far, both senators and the agency have tried to keep the declassification issue separate from their ongoing dispute.
Feinstein expressed hope that most of the summary and findings would escape CIA censors and reach the public within 30 days.
Sen. Jay Rockefeller, D-W.Va., said the report's public release is "the only way we can get this relationship with our intelligence agencies right again."