The report on the brutalities of the CIA’s secret prisons is the most important work by the Senate Intelligence Committee since congressional oversight of the CIA began in the 1970s. Its descriptions of torture and deception are as compelling as the newsreels of the Nuremberg trials.

But will it have any impact on the CIA or the future of congressional oversight? Not likely. Can Americans run a secret intelligence service under law in an open democracy? Not yet. We’ve been at it since 1947, but we’ve rarely gotten it right—and we’ve rarely gotten it more wrong than we did after 9/11.

The director of the CIA, John Brennan, much vilified for trying to defend the agency against the indefensible, was at least truthful in his public remarks after the report’s release: “We feared more blows from an enemy we couldn’t see and an evil we couldn’t fathom,” he said. “The agency was directed by President Bush to carry out a program to detain terrorist suspects around the world. In many respects, the program was uncharted territory for the CIA and we were not prepared. We had little experience housing detainees, and precious few of our officers were trained interrogators. But the president authorized the effort six days after 9/11 and it was our job to carry it out.”

In other words, the president told us to do it, and we did as we were told. But we didn’t know what we were doing.

It appears that the CIA did not give President Bush a full report on the gory details of the secret prisons for four years. This is “plausible deniability,” which shields the president from legal or moral hazard by keeping him in the dark. That practice was supposed to have ended decades ago.

The CIA had also forbidden the use of torture—“not only because it is wrong, but because it has historically proven to be ineffective,” in the words of Richard Stolz, chief of the clandestine service under Presidents Ronald Reagan and George H.W. Bush. Stolz is cited in the Senate report. The CIA’s codes of conduct before 9/11 clearly stated, “Inhumane physical or psychological techniques are counterproductive because they do not produce intelligence and will probably result in false answers.”

False answers were what Congress got from Bush’s CIA directors and their underlings. They delivered deceptive testimony and destroyed videotapes of torture. Brennan had to reprimand five officers for cybersnooping on the Senate’s files. The intelligence committees cannot function if the CIA lies to them and spies on them. That, too, was supposed to have ended when the committees were created in the 1970s.

To see how the system broke down, it’s best to know how it was set up.

Forty years ago, Director of Central Intelligence William Colby had a fateful conversation with a reporter for The New York Times, Seymour Hersh, who had discovered one of the CIA’s darkest secrets. On December 20, 1974, Hersh received a long-sought interview at the agency’s headquarters. Colby tried to argue that “family skeletons are best left where they are—in the closet,” but Hersh’s Page 1 headline read: “Huge C.I.A. Operation Reported in U.S. Against Antiwar Forces, Other Dissidents in Nixon Years.” The CIA had been spying on the American left, in violation of its charter.

Colby also tried to protect the agency by laying domestic spying at the doorstep of James Angleton, chief of the agency’s counterintelligence staff. Called before Congress, Angleton said, “It is inconceivable that a secret intelligence arm of the government has to comply with all the overt orders of the government.”

Watergate survivors like President Gerald Ford, Secretary of State Henry Kissinger and the highly influential White House staffer Donald Rumsfeld feared for the survival of the agency. On January 4, 1975, Ford told Kissinger and Rumsfeld, among others gathered in the Oval Office, that “the CIA would be destroyed” if more secrets leaked.

Ford, guided by Rumsfeld, set up a commission led by Vice President Nelson Rockefeller to report on the domestic activities of the CIA. Damage control was paramount; the report was a whitewash. The House select committee to investigate the CIA fell apart, but the Senate select committee’s staff and chairman, Frank Church, uncovered failed assassination plots against foreign leaders like Fidel Castro and conclusively demonstrated that the National Security Agency as well as the CIA had been spying on Americans.

The Church committee staff’s work, after long struggle, led to the permanent establishment of the congressional oversight committees we have today, along with the Foreign Intelligence Surveillance Court, the only judicial overseer for electronic eavesdropping.

Americans found hard to swallow the revelation that their presidents had authorized assassination plots against foreign leaders. Only through the vigilance of Congress did that come to light. And now we have to live with the equally unpleasant fact that we re-elected a president and vice president who thought torture is a legitimate tool of counterterrorism.

In part, the blame lies with Congress, which became a sleeping watchdog after the Cold War. Congress could have created an independent truth commission or a twenty-first-century Church committee. But it’s too late now; we are left with a once-in-a-generation report on the misdeeds of the past.

Senator Church, a former army intelligence officer, made one crucial misjudgment: he called the CIA a “rogue elephant.” Yet with a few significant exceptions, the rogue has been the president, and Congress has lacked the courage to condemn presidents over covert operations, even clearly illegal ones. CIA officers did not sit around a campfire in Afghanistan and say, “Hey, I’ve got a great idea! Let’s torture these guys!” No, that was the president, the vice president, their lawyers and gung ho CIA officials who saluted smartly and carried out their orders. That defense didn’t work at Nuremberg, and it shouldn’t work for Bush, Cheney and their unconstitutional claim that a state of war makes a president a king. But it will if the next Congress reverts to a state of willful ignorance about secret government, or the next president asserts an imperial dominion over international law.