A gripping battle between the Central Intelligence Agency and the Senate Intelligence Committee broke into public view Tuesday morning, as Senator Dianne Feinstein openly accused the CIA of spying on congressional staffers as they investigated the agency’s illegal detention and interrogation programs under President George W. Bush.

Feinstein’s allegations raise grave questions about how the executive branch interprets constitutional separation of powers, along with raising serious concerns about the integrity of congressional oversight of US intelligence agencies. And lurking in the background is the country’s dirty history of torture following the September 11 terror attacks, which top officials—including those appointed by President Obama—seem determined to brush into the dustbin of history.

In a lengthy speech on the Senate floor Tuesday morning, which you can read here, Feinstein explained how the Senate Intelligence Committee, which she chairs, has come to believe that the CIA infiltrated Senate computers in order to see what investigators had learned about the Bush-era torture programs. She also described the removal of crucial documents from those computers by the CIA.

How We Got Here

The backstory is crucial here, and the issues of congressional oversight and constitutional separation of powers echo throughout.

In 2002, the Bush administration authorized the CIA to begin detaining terror suspects and subjecting them to “enhanced interrogation techniques”—measures that most people now recognize with the less sanitary word: torture.

For years, members of the Senate Intelligence Committee were unaware of this program, save the chair and vice chair. The full committee was abruptly informed of the program by then-CIA Director Michael Hayden in September 2006, only hours before President Bush announced the existence of the program to the public. About a year later, The New York Times reported that the CIA was destroying videotapes of the first “enhanced” interrogations conducted by the agency.

By then, Democrats had taken control of the Senate and demanded answers. Hayden explained to the committee that the videotapes had to be destroyed, but that the CIA possessed paper records and operational cables that were “a more than adequate representation” of what was on the video tapes. He allowed committee investigators to review those documents, which they did over a period of years, culminating in 2009.

What they found was “chilling,” in the words of Feinstein this morning—the interrogations were “far different and far more harsh” than what the CIA had been admitting. Feinstein then wanted a full review of the program by Senate Intelligence Committee, which it approved by a 14-1 vote.

Initially, as she noted this morning, Feinstein wanted the CIA to turn over all relevant documents to the committee in their usual offices, as had been done in the past. Then—CIA Director Leon Panetta, who had been appointed by Barack Obama and confirmed just a month earlier, had other ideas.

Panetta wanted the review to take place at a secure CIA facility in Northern Virginia—something that would seem to undermine an independent congressional review. But, as Feinstein outlined in her speech Tuesday, an agreement was reached with agency officials in which the Senate review would take place on secure computers, but at the CIA facility:

Per an exchange of letters in 2009, then-Vice Chairman Bond, then-Director Panetta, and I agreed in an exchange of letters that the CIA was to provide a “stand-alone computer system” with a “network drive” “segregated from CIA networks” for the committee that would only be accessed by information technology personnel at the CIA—who would “not be permitted to” “share information from the system with other [CIA] personnel, except as otherwise authorized by the committee.”

It’s important to understand that this computer system in effect belonged to Congress, which was conducting crucial oversight of the executive branch as protected by the Constitution. It was this computer system that Feinstein alleges was infiltrated by the CIA.

The CIA began transferring hundreds of thousands, and then millions, of documents related to the enhanced interrogation program to these Senate computers. But it didn’t take long for problems to arise. In 2010, Senate investigators realized that the CIA had removed over 900 files it had initially transferred to them—something Feinstein revealed for the first time Tuesday morning during her speech on the Senate floor.

At first the CIA claimed no files had been removed, then blamed it on the private contractors who were helping the agency vet the documents, and then ultimately blamed it on an order from the White House. The administration denied giving any such order and brokered a peace between Feinstein and the CIA, which included a CIA apology.

But soon a far more severe breach arose.

The Internal Panetta Review

Let’s skip ahead a little bit first, and then get to the other, more crucial breach. In December 2012, the Intelligence Committee completed its 6,300-page review of the Bush administration’s torture programs. The public has not seen this report, as it remains classified, but it has been described as “searing” and highly critical of the CIA and the Bush administration. The CIA has reviewed the report and agrees with some of it, but disagrees strongly with other parts—generally the most damning ones.

But that public stance directly conflicts internal agency analysis. Over the course of the committee investigation, staffers discovered what has been come to be known as the internal “Panetta review.” This was essentially a report ordered by Panetta examining the documents that were being turned over to Congress, in an effort to get a grip on what exactly was being revealed. The committee has a partial version of this review on its computers, Feinstein said, as well as a printed-out, redacted hard copy in a secure location inside the Hart Senate Office building.

By all accounts, the Panetta review is damning. The public first learned of it in December, when Senator Mark Udall referenced it in an open confirmation hearing for CIA General Counsel Dianne Krass. “It appears that [the CIA’s internal detention and interrogation program review], which was initiated by former Director Panetta, is consistent with the Intelligence committee’s report, but amazingly it conflicts with the official CIA response,” Udall said during the hearing.

Feinstein also described the Panetta review this morning as quite critical of the CIA programs, and described “analysis and acknowledgement of significant CIA wrongdoing.”

Naturally the Panetta review is a monumentally important document that appears to undermine—in the CIA’s own words—the agency’s public dismissals of the most serious criticisms of Bush-era torture. It is this document that Feinstein alleged Tuesday morning was taken from Senate computers by the CIA.

Here’s what Feinstein described Tuesday morning:

At some time after the committee staff identified and reviewed the Internal Panetta Review documents, access to the vast majority of them was removed by the CIA. We believe this happened in 2010 but we have no way of knowing the specifics. Nor do we know why the documents were removed. The staff was focused on reviewing the tens of thousands of new documents that continued to arrive on a regular basis. […]

Shortly [after Udall’s comments], on January 15, 2014, CIA Director Brennan requested an emergency meeting to inform me and Vice Chairman Chambliss that without prior notification or approval, CIA personnel had conducted a “search”—that was John Brennan’s word—of the committee computers at the offsite facility. This search involved not only a search of documents provided to the committee by the CIA, but also a search of the ”stand alone” and “walled-off” committee network drive containing the committee’s own internal work product and communications.

According to Brennan, the computer search was conducted in response to indications that some members of the committee staff might already have had access to the Internal Panetta Review. The CIA did not ask the committee or its staff if the committee had access to the Internal Review, or how we obtained it.

Instead, the CIA just went and searched the committee’s computers.

A short time later, CIA Director John Brennan was interviewed at a Council on Foreign Relations event by NBC News’s Andrea Mitchell. He denied “spying” on the Senate, though closely examined, his language does not directly contradict what Feinstein alleged on the Senate floor only hours earlier.

“We weren’t trying to block anything,” Brennan said. “The matter is being dealt with in an appropriate way, being look at by the right authorities, and the facts will come out,” he added. “But let me assure you the CIA was in no way spying on [the committee] or the Senate.” He also denied “hacking.” Depending on how one defines spying and hacking, it’s possible Brennan was still allowing for the existence of the “search” that Feinstein alleges Brennan himself disclosed to her.

The Implications

If what Feinstein alleges is true, it essentially amounts to a constitutional crisis. And she said as much during her speech, describing “a defining moment for the oversight of our intelligence community.”

“I have grave concerns that the CIA’s search may well have violated the separation of powers principles embodied in the United States Constitution, including the Speech and Debate clause. It may have undermined the constitutional framework essential to effective congressional oversight of intelligence activities or any other government function,” Feinstein said. “Besides the constitutional implications, the CIA’s search may also have violated the Fourth Amendment, the Computer Fraud and Abuse Act, as well as Executive Order 12333, which prohibits the CIA from conducting domestic searches or surveillance.”

There’s also the issue of intimidation. The media reports that have been bubbling up recently around this issue have suggested that Senate investigators illegally obtained the Panetta review—some even raised the specter of hacking by the Senate investigators. The CIA went so far as to file a crime report with the Department of Justice, accusing Senate staffers of illegally obtaining the Panetta review.

Tuesday morning, Feinstein strenuously denied the review was illegally obtained, and asserted it was included in the 6.2 million files turned over by the CIA and describing at length why Senate lawyers felt it was a lawful document for the committee to possess.

And, in a remarkable statement, Feinstein accused the CIA of intimidation by filing the crime report. “[T]here is no legitimate reason to allege to the Justice Department that Senate staff may have committed a crime. I view the acting general counsel’s referral [to DoJ] as a potential effort to intimidate this staff—and I am not taking it lightly.”

Feinstein went on to note one fairly amazing fact. The (acting) general counsel she referred to, who filed the complaint with DoJ, was a lawyer in the CIA’s counterterrorism center beginning in 2004. That means he was directly involved in legal justifications for the torture program.

“And now this individual is sending a crimes report to the Department of Justice on the actions of congressional staff,” she noted gravely. “The same congressional staff who researched and drafted a report that details how CIA officers—including the acting general counsel himself—provided inaccurate information to the Department of Justice about the program.”

Remaining Questions

There are several crucial questions going forward.

(1) What else did the CIA do to conduct surveillance on the committee? Feinstein included an interesting aside in her speech. “Let me note: because the CIA has refused to answer the questions in my January 23 letter, and the CIA inspector general review is ongoing, I have limited information about exactly what the CIA did in conducting its search.” This seems to strongly suggest the CIA took other measures to conduct surveillance on Congress besides broaching the committee computer system.

What may these have been? There are a couple possibilities, though we should stress this is pure speculation.

During her speech, Feinstein went to great lengths to describe how the committee also had a physical copy of portions of the Panetta review secured inside the Hart Senate Office Building. She stressed that the documents were properly redacted and transported, and described how access to them is controlled.

Is it possible the CIA gained access to that room to see what the committee possessed in hard-copy form? Again, we should stress Feinstein does not allege this, and that she also said the copy “remains” in Hart. But it would be reasonable to think that if the CIA went to such lengths to see what the committee had in electronic form, it might want to see the physical copies as well. While hacking versus a breaking-and-entering intrusion into a physical space is a distinction without any real difference in a legal sense, a physical CIA break-in of Senate offices would no doubt crank up the temperature of this imbroglio by several degrees.

Also: remember that earlier this year, in response to a question from Senator Bernie Sanders, the National Security Agency did not expressly deny spying on Congress. The NSA may just have been being careful with its language, reasoning that since bulk data collection exists, perhaps members of Congress were caught up in it. But the question remains: if the CIA felt justified spying on Senate computers, may it have listened in on phone calls as well?

(2) Will Obama respond, and what will he say? Feinstein’s grave concerns were echoed Tuesday morning by Senator Patrick Leahy, chair of the Senate Judiciary Committee. “This is not just about getting to the truth of the CIA’s shameful use of torture. This is also about the core founding principle of the separation of powers, and the future of this institution and its oversight role,” Leahy said in a statement. “The Senate is bigger than any one Senator. Senators come and go, but the Senate endures. The members of the Senate must stand up in defense of this institution, the Constitution, and the values upon which this nation was founded.”

So we have the respective chairs of the Senate Intelligence and Senate Judiciary Committees publicly accusing the executive branch—which is controlled by their own party—of stepping across a very serious constitutional line. It cannot be stressed enough that this is a serious crisis.

Can President Obama, himself a constitutional law scholar, avoid comment? If not, what will he say?

For the moment, the White House is saying nothing. Press Secretary Jay Carney gave very little in the way of answers or opinions Tuesday afternoon during his daily briefing, and declined to even characterize Obama as “concerned.” Carney also expressed the president’s “great confidence” in Brennan and the intelligence community.

(3) Will the Senate Intelligence report on Bush-era torture ultimately be declassified? Underlying this constitutional crisis is a desire by many at the CIA to sweep the Bush-era torture abuses under the rug. That logically would be the clear motivating factor in seizing the Panetta review from Senate investigators.

And Brennan wasn’t afraid to keep pushing that approach—even during the same Tuesday interview with NBC’s Mitchell in which he denied “spying” on the Senate. Brennan also said that the CIA’s history of detention and interrogation should be “put behind us.” (It should be noted, of course, that there is strong circumstantial evidence that Brennan himself was complicit in the illegal torture program when he served in the Bush administration.)

In the wake of her revelations on Tuesday, Feinstein renewed her desire to declassify the Senate report. “We’re not going to stop. I intend to move to have the findings, conclusions and the executive summary of the report sent to the president for declassification and release to the American people,” she said, and suggested the findings will shock the public. “If the Senate can declassify this report, we will be able to ensure that an un-American, brutal program of detention and interrogation will never again be considered or permitted.”

Obama has long said he supports declassification, and it seems it will happen soon. Tuesday, Feinstein was already moving to hold a committee vote on declassification. Committee Republicans will likely oppose it, but independent Senator Angus King, the swing vote, told reporters he is inclined to vote for declassification.