United States Supreme Court Justice Clarence Thomas — a conservative judge on the nine-member bench that makes up the highest court in the country — has failed to disclose years of luxury trips he received from a donor, according to a report by ProPublica.

The omissions appear to violate a financial disclosure law that requires justices — as well as federal judges, members of Congress and other officials — to disclose most gifts, the nonprofit news organisation said on Thursday.

The report also raised questions about the sway outside influences might have over the Supreme Court, which is the final arbiter of US law. Its decisions have wide-ranging effects on the lives of US residents.

Citing documents and interviews, ProPublica found that Thomas took regular rides on Republican megadonor Harlan Crow’s private jet and 162-foot (50-metre) yacht.

None of those trips were reported in Clarence’s annual financial disclosures, according to the news outlet.

Thomas did not respond to ProPublica’s request for comment. However, in a statement, Crow said that he and his wife have “been friends with Justice Thomas and his wife [Virginia ‘Ginni’ Thomas] since 1996”.

“The hospitality we have extended to the Thomas’s over the years is no different from the hospitality we have extended to our many other dear friends,” said Crow, who has for decades used his wealth to support conservative causes.

“Justice Thomas and Ginni never asked for any of this hospitality. We have never asked about a pending or lower court case, and Justice Thomas has never discussed one, and we have never sought to influence Justice Thomas on any legal or political issue.”

NEW BLOCKBUSTER: Private jet travel. Superyacht Island-hopping. Stays at a private resort.

For decades, Justice Clarence Thomas accepted luxury gifts from a billionaire.

Appears he broke the law.@js_kaplan & @JustinElliott: https://t.co/Ltij24cHJA pic.twitter.com/tG9HM5OsVT

— Jesse Eisinger (@eisingerj) April 6, 2023

Crow added that he was “unaware of any of our friends ever lobbying or seeking to influence Justice Thomas on any case, and I would never invite anyone who I believe had any intention of doing that”.

Among the recent trips detailed in the report was a 2019 Indonesian vacation, valued at more than $500,000. Another was an extended cruise in New Zealand roughly a decade ago.

ProPublica also said it found evidence that Thomas regularly flew on Crow’s Bombardier Global 5000 jet for both domestic and international flights.

Supreme Court justices are generally required to report any gifts, including travel, valued at more than $415.

Questions about resort stays

The ProPublica report also raised questions about Thomas’s regular stays at Crow’s lakeside resort in the New York Adirondacks.

The law says that “food, lodging, or entertainment received as personal hospitality need not be reported”. But ProPublica noted that Crow’s resort is owned through a company, meaning Thomas could have still been required to document his stays there.

Thomas has vacationed at the resort alongside executives from Verizon and PricewaterhouseCoopers, major Republican donors. His stays also overlapped with that of a leader representing the American Enterprise Institute, a conservative think tank, according to ProPublica.

A painting at the resort shows Thomas chatting with Leonard Leo, the leader of the Federalist Society, a legal organisation that observers said has been instrumental in orchestrating the Supreme Court’s rightward lurch, the report said.

Ongoing ethical concerns

Thomas, who was appointed to the Supreme Court in 1991, has since become one of its most conservative voices.

During his tenure, Thomas has been no stranger to controversy. He was confirmed to the bench despite sexual harassment allegations by former staffer Anita Hill, accusations he has denied.

That his wife Ginni works as a conservative activist has also raised potential conflicts of interest for Thomas. Critics have pointed out that her work occasionally overlaps with the issues before the Supreme Court.

Last year, for instance, Thomas refused to recuse himself as the court weighed cases related to the 2021 Capitol attack, despite his wife’s support for efforts to overturn the 2020 presidential election results.

US media published 29 text messages showing Ginni Thomas urged former President Donald Trump’s Chief of Staff Mark Meadows to stand by the lie that the election had been stolen. She called it the “greatest Heist of our History”.

A history of gifts

For his part, Crow, who inherited his parent’s real-estate empire, has repeatedly given gifts to the Thomases. They include a $19,000 Bible that belonged to famed abolitionist Frederick Douglass, which Clarence Thomas did list in his financial disclosures.

According to the news publication Politico, Crow also gave approximately $500,000 to Liberty Central, a group Ginni Thomas founded in 2009 that was linked to the conservative Tea Party movement.

He also helped to finance a Georgia library dedicated to Thomas, the New York Times reported in 2011.

In his statement to ProPublica, Crow said he and his wife will continue to support projects “to make sure as many people as possible learn about [Thomas], remember him, and understand the ideals for which he stands”.

He added: “[Clarence and Ginni Thomas] never asked us to do any of this”.

This cries out for the kind of independent investigation that the Supreme Court — and only the Supreme Court, across the entire government— refuses to perform.https://t.co/d24CQLAdo9

— Sheldon Whitehouse (@SenWhitehouse) April 6, 2023

Reaction at Congress

Following the publication of the ProPublica report, Senator Dick Durbin, the Democratic chairman of the Senate Judiciary Committee, called on legislators to pass a bill that would create an ethical conduct code for Supreme Court justices and a special counsel to investigate ethics issues.

“The highest court in the land shouldn’t have the lowest ethical standards,” he said, adding that the reported behaviour “is simply inconsistent with the ethical standards the American people expect of any public servant, let alone a Justice of the Supreme Court”.

He called the report a “call to action, and the Senate Judiciary Committee will act”.

Meanwhile, Democratic Senator Sheldon Whitehouse said the report “cries out” for an independent investigation.

Meanwhile, Representative Ted Lieu, a Democratic member of the House Judiciary Committee, called on Clarence to resign.

“Is Supreme Court Justice Clarence Thomas corrupt? I don’t know,” he tweeted. “But his secretive actions absolutely have the appearance of corruption. And he apparently violated the law. For the good of the country, he should resign.”