WASHINGTON — Roger J. Stone Jr., a close ally of former President Donald J. Trump, on Thursday sued members of the House committee investigating the Jan. 6 attack on the Capitol, asking a federal court to block them from obtaining logs of his texts and phone calls as part of what he deemed an effort to persecute him and other conservatives.
With the suit, which also named Speaker Nancy Pelosi, Mr. Stone joined at least 19 potential witnesses who are fighting the committee’s subpoenas in court, though judges have thus far sided with the panel, ruling that congressional investigators have broad power to access evidence for the inquiry. Those seeking to use the courts to stonewall the committee include Mark Meadows, the former White House chief of staff, as well as lower-level witnesses who helped to organize the rally in Washington that preceded the Capitol riot.
Mr. Stone’s lawsuit attacked the legitimacy of the investigation, and argued that the committee’s request for his communications records was “overly broad.” In particular, it objected to a subpoena the panel had sent AT&T this month that demanded access to his mobile phone data including “all calls, text messages, and other records of communications” associated with his number.
It also sought information about his IP addresses, which identify devices on a network; billing addresses; a list of contacts; call session times; and other metadata spanning a broad time frame from before the 2020 election until weeks after the violence at the Capitol: Nov. 1, 2020 to Jan. 31, 2021.
The suit also claimed that the panel was harassing Mr. Stone because he is part of the conservative movement.
“The select committee is probing plaintiff because of his political belief,” it said, alleging without evidence that the information would be used to build “a massive database” to track Mr. Stone and like-minded associates who believe in “election integrity” or “government skepticism.”
The committee’s investigators see Mr. Stone as a crucial witness for several reasons, including that he, perhaps uniquely among those subpoenaed by the committee, has relationships with some of the most prominent political organizers and far-right groups involved in the rallies that preceded the Capitol attack.
In a ruling in a civil suit last week, a federal judge in Washington noted that Mr. Stone had been in contact with the leader of Proud Boys militia group and later used the Oath Keepers as his security detail for the rally on Jan. 6, 2021. Members of the Oath Keepers have been charged with seditious conspiracy over what prosecutors said was their wide-ranging plot to storm the Capitol on that day and disrupt the formal count in Congress to confirm Joseph R. Biden Jr.’s electoral victory.
“Stone’s connections to both the president and these groups in the days leading up to Jan. 6 is a well-pleaded fact,” Judge Amit P. Mehta wrote as he allowed civil suits against Mr. Trump over Jan. 6 to move forward. “Discovery might prove that connection to be an important one.”
In December, Mr. Stone appeared before the committee for a deposition but invoked his Fifth Amendment right against self-incrimination to each of the panel’s questions because, he said, he feared that Democrats would fabricate perjury charges.
Capitol Riot’s Aftermath: Key Developments
Mr. Stone claimed that he was leaving town as rioters stormed the Capitol and said he had condemned the day’s violence as “illegal and politically counterproductive.”
“I did not march to the Capitol. I was not at the Capitol,” he said.
The committee is not only examining at those who committed violence, but how plans to amass a crowd at the Capitol came into existence.
Mr. Stone and the conspiracy theorist Alex Jones were among the group of Trump allies meeting in and around the Willard Intercontinental Hotel near the White House the day before the riot — a meeting spot the committee views as an informal headquarters for plans to overturn the election.
He was seen flashing his signature Nixon victory sign to supporters and was also photographed on Jan. 5 with Michael T. Flynn, the former national security adviser who has also been subpoenaed and sued the committee.
A spokeswoman for the committee declined to comment on Mr. Stone’s suit.