CIA Director John Brennan’s decision to search Senate committee computers was such a blatant violation of the constitutional separation of powers that some pro-accountability groups in Washington are starting to seek his ouster.

Senate Intelligence Committee Chair Dianne Feinstein (D-Calif.) disclosed in a fiery speech on Tuesday that Brennan told her in January that CIA personnel had conducted a search on  computers at a CIA-leased facility that had been reserved for the use of committee staffers investigating the agency’s role in the Bush-era torture of detainees.

The Constitution clearly gives the legislative branch the authority to investigate the executive branch — and not the other way around.

More even than the act itself, some critics see Brennan’s lack of recognition of the extent of his violation of key constitutional principles to be the biggest cause for him to be fired.

“The recent revelations that CIA Director Brennan reported the surveillance directly to Chairman Feinstein is stunning,” said Angela Canterbury, public policy director of the Project On Government Oversight (POGO).

“How can we hold such impunity accountable? Remove Brennan, for starters,” she said. “And then there must be a full investigation that is more independent than one might expect from DOJ.”

Shahid Buttar, executive director of the Bill of Rights Defense Committee, said that the concerns about the Senate investigation that led Brennan to launch his search were “ridiculous, as well as simply incorrect.”

Buttar continued: “Given his false assurances to the Senate Intelligence Committee about CIA drone strikes, and his continuing failure to let the public finally know the facts about CIA torture, Brennan should resign or be removed from office so the Committee can examine and confirm new leadership.”

Some senators appeared to be close to calling for Brennan to go. “I’ve lost confidence in Director Brennan, particularly because he won’t acknowledge the misdeeds and misconduct of the CIA,” Sen. Mark Udall (D-Colo.)  said on MSNBC on Tuesday. He added: “The CIA has an important role to play, but if the public doesn’t trust the CIA, if the Senate overseers don’t trust the CIA, I don’t know how Director Brennan can continue to lead the agency.”

“Despite Director Brennan’s commitment to ‘strengthen the trust’ between the CIA and the Intelligence Committee, the relationship between our respective bodies has only deteriorated during the first year of his tenure,” Sen. Martin Heinrich (D-N.M), said in a statement.

Brennan, in his own remarks after Feinstein’s speech on Tuesday, vaguely ridiculed allegations of CIA “hacking” and said that “when the facts come out on this, I think a lot of people who are claiming that there has been this tremendous sort of spying and monitoring and hacking will be proved wrong.” But nothing he said actually disputed Feinstein’s version of events.

And as Michael Masnick reported for Techdirt, a January 27 letter to Feinstein that Brennan  sent out to CIA staff on Tuesday actually confirmed the search, though Brennan described it — and the need for it — in the context of concern about a security breach:

Because we were concerned that there may be a breach or vulnerability in the system for housing highly classified documents, CIA conducted a limited review to determine whether these files were located on the SSCI [Senate Select Committee on Intelligence] side of the CIA network and reviewed audit data to determine whether anyone had accessed the files, which would have been unauthorized.

And he said he wasn’t done. “Only completion of the security review will answer how SSCI staff came into possession of the documents,” he wrote, saying that he had only “temporarily” suspended further action until getting Feinstein’s consent.

The “breach” in question concerned the committee staff’s possession of an internal CIA review of the materials the agency had previously turned over to Feinstein’s committee during the course of the four-year congressional investigation into the Bush-era torture practices.

Feinstein said the document, which has become known as the Panetta Review because it was evidently prepared for then-director of the CIA Leon Panetta, was first discovered by committee staff using CIA-provided search tools in 2010. It became particularly relevant more than two years later, after the committee completed a scathing 6,300-page report in December 2012, and the CIA sent its official response in June 2013.

While the CIA officially rebutted key parts of the committee’s report, the internal review apparently corroborated them.

The CIA learned the committee was aware of the internal review in December 2013, which evidently caused them great alarm — either because of concerns about a “security breach” or because, as Feinstein put it, its “unique and interesting… acknowledgement of significant CIA wrongdoing.”

Feinstein said Tuesday that she responded to Brennan’s January visit with several letters expressing her concerns that the action was illegal and unconstitutional.

Brennan’s letter in response shows him glibly dismissing her complaints:

I wholeheartedly agree that the Executive and Legislative branches must respect the Constitution’s separation of powers and that the events that led up to our meeting go not only to the heart of that respect, but also to the effectiveness and integrity of the oversight process…. [I]t is my hope that we can find a way to address these events in a mutually satisfactory way that respects the very separation of powers principles we both seek to uphold.

The separation of power principles establish how the three branches of government interact and serve as checks and balances to each other. Congress, for instance, writes laws, which the president can veto or the courts can overrule. The executive branch enforces the laws. As for investigations, as  Sen. Martin Heinrich (D-N.M) felt the need to state last week: “The Senate Intelligence Committee oversees the CIA, not the other way around.”

The search of a congressional computer — without notice, without a warrant, without any clear indication of criminal activity — is so clearly over the line that Pete Hoekstra, a former Republican chairman of the House Permanent Select Committee on Intelligence, told the Daily Beast: “I don’t know if Brennan can survive at this point.”

Three unnamed former intelligence officials told Foreign Policy it appeared Brennan had violated the basic rule “that staff should be free of any interference by executive branch officials they’re charged with overseeing and should avoid even the appearance of meddling with an inquiry.”

White House Press Secretary Jay Carney, meanwhile, insisted on Tuesday that “The President has great confidence in John Brennan.”