The lifestyle Justice Clarence Thomas has enjoyed over the last three decades bankrolled by gifts and hospitality from his wealthy friends is more extensive than previously known, according to a new ProPublica report, and has included numerous flights on private planes, skybox tickets to sporting events, stays at luxury resorts, and a standing invitation to play at a high-end private golf club in Florida.

The new report is the broadest look yet at how Thomas' social circle has funded -- with limited disclosure to the public -- a regular stream of extravagant excursions and events since he became a Supreme Court justice. These costly trips and travel perks often went unreported on the justice's financial disclosure forms, ProPublica said in its investigation.

Thomas is already under intense scrutiny for gifts he received from Harlan Crow, a GOP megadonor who treated Thomas and his wife to extravagant vacations, paid for the tuition of a Thomas family member and entered into an unusual real estate transaction related to the home of Thomas' mother. In April, Thomas released a statement defending his friendship with Crow. "As friends do, we have joined them on a number of family trips during the more than quarter century we have known them," Thomas wrote.

The latest investigation unearths a pattern of gifts to Thomas from Crow and three other billionaires who have been major contributors to Republican causes: David Sokol, the former heir apparent of Berkshire Hathaway; the late H. Wayne Huizenga, who made his vast fortune in his ownership of Blockbuster, Waste Management Inc. and other major companies; and Paul "Tony" Novelly, who formerly owned an oil company.

ProPublica interviewed more than 100 people, including staff that would have worked some of the trips that Thomas took. It also reviewed records obtained from the US Marshals Service, tax court filings, and personal photographs.

Thomas did not respond to ProPublica's detailed list of questions for its report, nor did Novelly. Huizenga died in 2018, and his son, who leads the family business, also did not respond to ProPublica's inquiries.

Sokol acknowledged in a statement to ProPublica that he hosted the Thomases. "We have never once discussed any pending court matter," Sokol said. "Our conversations have always revolved around helping young people, sports, and family matters."

"As to the use of private aviation," he added, "I believe that given security concerns all of the Supreme Court justices should either fly privately or on governmental aircraft."

Both the lack of transparency about his financial relationships with Republican megadonors, and the jet-setting lifestyle he's enjoyed because of those friendships, put Thomas out of step with how lower court judges and other government officials approach their ethical obligations, legal experts told ProPublica.

While several other Supreme Court justices have been accused of bending or breaking ethical rules when it comes to accepting and disclosing gifts, ProPublica's reporting shows that Thomas especially has operated under a different set of ethical norms than federal judges on lower courts -- and even the courts' counterparts serving in other branches of government, which are covered by the same financial disclosure law that applies to the judiciary.

Jeremy Fogel, a former judge who for years reviewed lower court judges' financial disclosures, told ProPublica the amount of undisclosed gifts Thomas received is unlike anything he's ever seen.

"In my career I don't remember ever seeing this degree of largesse given to anybody," said Fogel. "I think it's unprecedented."

The new revelations also raise questions about whether Thomas broke the law with his failure to report at least some of the gifts and hospitality he received. Ethics experts who spoke to ProPublica said some of the hospitality he received, like when his friends hosted him at their personal homes, may not have required disclosure, but that other types of gifts, such as the costly tickets he received to major sporting events, should have been reported.

The conduct and financial relationships of other Supreme Court justices have been questioned for ethical reasons, but those allegations have so far not matched the lavishness of the hospitality that Thomas has received, nor has any other justice been accused of such an extensive pattern of failing to disclose such transactions.

None of the Thomas benefactors highlighted in the new report appear to have had direct business in front of the Supreme Court, ProPublica said. However, their donations to political causes on the right put them in sync with the justice's far-right jurisprudence, and the friendships that were the source of the gifts and hospitality confirmed by ProPublica all seem to have begun after Thomas joined the most powerful court in the country. The three new billionaires that ProPublica is throwing into the mix with the new investigation share a connection to Thomas via the Horatio Alger Association, an exclusive organization that fundraises for student scholarships and mentorships; Thomas' involvement in the group was the subject of a New York Times report last month.

Though the total value of the recently revealed gifts is unclear, ProPublica estimated that they are likely in the millions of dollars.

The new reporting comes as Democrats in Congress, propelled by the apparent ethical lapses of Thomas and other justices, have made the lack of a firm ethics code for the justices a major focus. The Supreme Court follows some of the financial disclosure rules mandated for lower courts judges, but in a statement earlier this year, the justices indicated that they believed they were doing so voluntarily. The justices are also not subject to other procedures used in lower courts to address potential conflicts of interest.

Chief Justice John Roberts and other members of the court -- as well as many Republicans on the Hill -- have signaled that they believe that the justices can be trusted to police themselves on ethical issues. Roberts has also hinted that the court may take additional steps to firm up its ethics practices, however public comments from other justices, and particularly from Justice Samuel Alito, suggest there's resistance in the court to succumbing to the current pressure for ethics reform.

The report is the latest in a series of investigations into the failure of justices, and Thomas in particular, to report on annual financial disclosure forms the gifts and hospitality they have received. The initial rounds of ProPublica reporting focused on Thomas' relationship with Crow, a billionaire real estate titan who has donated to millions to Republican-aligned causes, and whose gifts and hospitality towards the justice went unreported, with a few exceptions, on Thomas' financial disclosure forms.

Thomas intends to amend his financial disclosure forms, a source close to the justice previously told CNN, to at least reflect Crow's 2014 purchase of Thomas' mother's home. ProPublica previously reported that the deal allowed her to continue to live on the property at least through 2020, while Crow paid for renovations to the home.

Thomas has also recently been scrutinized for an undisclosed loan he received, reported by The New York Times last week, from a wealthy friend to pay for a $267,230 RV he purchased in 1999. The friend, Anthony Welters, who has been a major Democratic fundraiser and whose wife served as an ambassador in the Obama administration, told the Times the loan had been "satisfied" but declined to detail on what terms.