The Senate Judiciary Committee authorized subpoenas on Thursday for conservative allies of Justices Clarence Thomas and Samuel A. Alito Jr., acting over angry objections from Republicans to secure more information about luxury travel, gifts and other benefits provided to members of the Supreme Court.
The panel concluded an acrimonious session with Republicans storming out as Democrats voted to approve subpoenas for Leonard Leo, a leading conservative judicial activist, and the billionaire Republican donor Harlan Crow. They were the latest steps in the committee’s inquiry into the court after a series of media reports about undisclosed trips and real estate deals.
Senator Richard J. Durbin, Democrat of Illinois and chairman of the panel, called the men “central players” in what he described as an ethics crisis on the Supreme Court. He said the committee needed to uphold Senate authority after the men refused for months to cooperate with the panel about their interactions with the justices.
“Their attempts to thwart the legitimate oversight efforts of Congress should concern us all,” Mr. Durbin said.
Republicans expressed outrage at the move, accusing Democrats of trying to undermine the court after a series of conservative rulings on abortion rights and other issues. Republicans boycotted the committee vote after Democrats prevented their bid to block it with procedural tactics. G.O.P. senators threatened repercussions for the narrowly divided panel, which is responsible for handling judicial nominations, key executive branch appointments and immigration among other issues, and relies on some level of bipartisan cooperation.
“I have tried as the ranking member — to my own detriment — to get things moving through this committee because I realize that elections matter,” said Senator Lindsey Graham of South Carolina, the senior Republican on the panel. “Those days are over. I consider this unacceptable.”
The session began on a sour note when Mr. Graham and other Republicans on the committee heatedly disputed a decision by Mr. Durbin not to allow them a chance to express their views on two judicial nominees facing a revote by the panel because of a G.O.P. procedural objection. Mr. Durbin said Republicans had two previous opportunities to address the nominations and that he was following precedents set by two former Republican chairmen. Republicans claimed they were being muzzled.
“Mr. Chairman, you just destroyed one of the most important committees in the United States Senate,” said Senator John Cornyn, Republican of Texas and a longtime member of the committee. “What goes around comes around.”
After the subpoena vote, Mr. Leo, who played a significant role in shaping the conservative-dominated Supreme Court by advising the Trump administration on nominees, said he did not intend to comply if Mr. Durbin issued such an order. ProPublica reported earlier this year that Mr. Leo, a longtime executive at the conservative Federalist Society, helped arrange and took part in a high-end Alaskan fishing trip with Justice Alito that was not reported on the justice’s financial disclosure forms.
“Senate Judiciary Committee Democrats have been destroying the Supreme Court; now they are destroying the Senate,” Mr. Leo said in a statement. “I will not cooperate with this unlawful campaign of political retribution.”
A statement from Mr. Crow’s office said he remained open to discussing his ties to Justice Thomas but that Democrats “have made intrusive demands of a private citizen that far exceed any reasonable standard and to this date have not explained why this request is necessary to craft legislation.”
Should the men refuse to comply, the full Senate would have to vote to take steps to enforce the subpoena, and Republicans vowed that they would filibuster any such effort should it reach the Senate floor.
“You are going to meet a brick wall,” said Mr. Graham, who said Democrats were waging a “jihad” against the current court. “You have made a terrible decision.”
Earlier in November, the Supreme Court announced a new code of ethics, saying that justices had already been abiding by much of it. Critics said the provisions did not include enforcement mechanisms, and on Thursday Mr. Durbin said the standards were lacking.
“The court’s new code of conduct falls far short of what we should expect for the highest court in the land,” said Mr. Durbin. He sought to rebut claims that he was driven by his opposition to recent court rulings by noting that he has been pushing for more than a decade for a new code of conduct for the Supreme Court.
“An enforceable code of conduct would apply to all nine justices, appointed by presidents of both parties,” he said.
Given recent Supreme Court confirmation battles, the Judiciary Committee is not unfamiliar with such partisan rancor. One Democrat noted how incensed their members were with the Republican handling of the confirmation of Justice Brett M. Kavanaugh.
“Furies are temporary in the Senate,” said Senator Sheldon Whitehouse, Democrat of Rhode Island and a senior committee member.
