WASHINGTON — A mysterious incident has loomed over a fight in Congress over reauthorizing an expiring warrantless surveillance law: About three years ago, a Federal Bureau of Investigation analyst violated the rules for searching a repository of messages intercepted by the program by making overly broad queries about an undisclosed member of Congress.
The conversation about that incident, which became public with few other details in a footnote of a report that was declassified in December, underwent a startling twist on Thursday at a House Intelligence Committee hearing. An Illinois Republican, Representative Darin LaHood, identified himself as that lawmaker.
“I have had the opportunity to review the classified summary of this violation, and it is my opinion that the member of Congress who was wrongfully queried multiple times solely by his name was, in fact, me,” he said from the dais.
Mr. LaHood is not just any random lawmaker. He is the leader of a bipartisan working group of Intelligence Committee members who are trying to persuade Congress to reauthorize the warrantless surveillance law in question, known as Section 702.
Section 702 authorizes the government to collect, without a warrant and from American companies like Google and AT&T, the private messages of targeted foreigners abroad — even when they are communicating with Americans. The F.B.I.’s ability to search for information about Americans in the repository of intercepted messages has been a focus of controversy.
Elected to Congress in 2015, Mr. LaHood is a former federal counterterrorism prosecutor and the son of Ray LaHood, who was also a Republican member of Congress from Illinois and later served as transportation secretary in the Obama administration.
Mr. LaHood provided no further details about the incident. But he was scathing in his remarks to the committee, calling the queries about communications involving a member of Congress an egregious violation that betrayed trust in government surveillance power and could be “seen as a threat to the separation of powers.”
At the same time, he made clear that he still believes that Congress must reauthorize Section 702, which he praised as a vital tool for combating a broad range of foreign threats. Citing F.B.I. abuses, he told a lineup of witnesses that the government needed to do more to build trust with the public and Congress to win the law’s extension.
“This careless abuse of this critical tool by the F.B.I. is unfortunate,” he said. “Ironically, I think it gives me a good opportunity and a unique perspective on what’s wrong with the F.B.I. and the problems that the F.B.I. has.”
While lawmakers reauthorized Section 702 in 2012 and 2018, its prospects for extension face steeper odds this time. Civil libertarians, who have long been skeptical of Section 702 because of its impact on Americans’ privacy, have been joined by Republicans who share former President Donald J. Trump’s distrust of security agencies and surveillance.
Mr. LaHood pointed to a recently declassified report, which discussed “compliance incidents” in which officials violated rules for searching the repository of collected messages during a six-month period from late 2019 to mid-2020.
Most involved queries for unapproved purposes, like vetting maintenance workers and potential informants. But one involved the politically charged matter of an F.B.I. analyst’s inappropriate requests for messages involving a congressman, whom the report did not identify. It said the query had returned raw messages intercepted under Section 702, which were opened and read.
As laid out in the report, the problem was not that the analyst had asked for information about a congressman. The report said there were documented facts that led the analyst to make the requests, and while it did not say what they were, it did not criticize the rationale.
Rather, the report said the Justice Department and the Office of the Director of National Intelligence deemed the queries “overly broad as constructed,” because the analyst improperly only used the congressman’s name as a single broad search term, without also using limiting terms to narrow any results to material about the specific topic at hand.
Last month, Representative Andy Biggs, Republican of Arizona, pressed the F.B.I. director, Christopher A. Wray, to provide details of the incident — including demanding to know whether the lawmaker in question had been told.
Mr. LaHood said the “report’s characterization of this F.B.I. analyst’s action as a mere misunderstanding of querying procedures is indicative of the culture that the F.B.I. has come to expect and even tolerate.”
“It’s also indicative of the F.B.I.’s continued failure to appreciate how the misuse of this authority is seen on Capitol Hill,” he said.
But he also used most of the remainder of his time to introduce material about changes the F.B.I. has made to its systems and training since summer 2021 that led to a drop in requests for information about communications involving Americans, and to elicit testimony from witnesses about the program’s value in countering Chinese espionage.
The F.B.I. press office said in a statement that it could not comment on specific queries. But the statement cited “extensive changes” to better enforce compliance with rules for querying the 702 repository for information about Americans, which “post-date the period covered in the reports raised in the hearing today.”
It flagged one in particular: “‘sensitive’ queries involving elected officials now require deputy director approval.”
Julian E. Barnes contributed reporting.