It's undeniable that Justice Clarence Thomas' friendships with billionaires willing to foot his bill on their vacations together have given the conservative jurist a lifestyle most Americans could only dream of.

But determining whether Thomas violated ethics rules and laws by failing to disclose that hospitality is tricky.

The law in question is the Ethics in Government Act, and how it should be applied to the extravagant travel that Thomas and other justices have been treated to has been a subject of debate.

The debate centers on what counts as "personal hospitality" -- i.e., accommodations and entertainment that judges are treated to personally by their friends -- which does not have to be reported on annual financial disclosures under certain contexts.

The Supreme Court's critics note that, even if Thomas was not technically in violation of the rules, his pattern of accepting -- and not reporting -- lavish experiences such as skybox tickets to major sporting events and far-flung trips on mega-yachts shows that the high court cannot be trusted to police itself under the current standards. Some argue that more stringent ethical reforms -- perhaps in the form of legislation -- are needed.

Further complicating the picture is that the regulations laying out when personal hospitality need not be reported have recently been tightened. Thomas' defenders have pointed to those changes, announced earlier this year, to argue that the old regime did not require the justice to report the types of hospitality now under scrutiny. Thomas himself -- in a rare statement released in April, when ProPublica published its first investigation into the extravagant travel perks he has received -- noted that reworked ethical guidance and vowed to follow it going forward.

But assessing whether the gifts and hospitality described in the latest ProPublica report -- which puts the tally at 38 destination vacations, 26 private jet flights, eight helicopter trips and a dozen VIP tickets to sporting events -- would require disclosure, either then or under the tightened rules, is a complicated question. It sometimes depends on details about how the high-end trips were financed that were not fully fleshed out by the report.

"The question is: Who is absorbing the cost?" said Stephen Gillers, a New York University School of Law professor who has written extensively about legal ethics and rules.

Travel on private planes

Thomas is not the only justice who has engaged in such jet-setting. When Justice Samuel Alito was the subject of a ProPublica report detailing a 2008 private flight he took to Alaska on a plane owned by a GOP megadonor, he argued in a preemptive essay published by Wall Street Journal's opinion section that he was not required to disclose it under ethics rules in place at the time. Alito claimed that plane trip fit the definition of "facility" in the requirements' exemptions for personal hospitality extended to judges "on property or facilities owned by (a) person"

Ethics experts have pushed back on the idea that a private flight could be interpreted to fall under the term "facility." The new guidance announced in March makes clear that going forward, private plane trips cannot be excluded from the reporting requirements because "substitutes for commercial transportation" are not part of the exemptions.

ProPublica's latest report, published Thursday, surfaces several helicopter trips that Thomas took apparently at the expense of his billionaire benefactors. Even under the new guidance, there could be some argument that certain helicopter trips may not require disclosure, according to Gillers, who gave the example of a helicopter ride over the Grand Canyon.

Since such a ride would not be a replacement of a commercial flight, but instead a form of entertainment offered by a friend, disclosure could potentially be avoided. But another key question, under the new guidance, is whether the helicopter ride was being paid for personally by the friend of the judge.

The new guidance states that accommodations offered to a judge that are not paid for out of the personal pocketbook of an individual -- but through a third-party entity, which could include the friend's company or another business -- would require disclosure. If the person footing the cost is seeking a tax deduction for the expense of the accommodation or gift, that would also trigger a judge's reporting requirement.

That means if the helicopter rides described in the ProPublica report -- which Thomas occasionally enjoyed in the mid-2000s because of his friendship with the late corporate titan Wayne Huizenga -- were on a helicopter owned by Huizenga's business, Thomas would have to disclose them under the new rules. Even if Huizenga owned the helicopter personally, if he put the cost of the rides toward a tax exemption, that would also mean Thomas' helicopter jaunts would fall outside of the exemptions.

Stays on luxury yachts

Thomas' friendships with oil baron Paul "Tony" Novelly and real estate mogul Harlan Crow have led to the billionaires hosting him on their mega-yachts. Those trips have included ventures with Novelly in the Bahamas and island-hopping with Crow in Indonesia. Since Thomas presumably was sleeping on the yachts, he can argue they're covered by the disclosure exception for accommodations personally offered by friends.

"Thomas could say that, just as a weekend at a country home at the invitation of a friend is personal hospitality, a week on my friend's yacht is also personal hospitality. It's just that one is on the land and one is on the water," Gillers said.

VIP tickets to sporting events

Another area of scrutiny in the new ProPublica report is tickets to major sporting events -- often for skybox seats -- that Thomas received from his wealthy friends. Government ethics experts quoted in the story raised the disclosure requirement for gifts valued at more than $415 as potentially problematic for Thomas.

However, according to Gabe Roth, who heads the organization Fix the Court, the ethics questions over the tickets hinge more on the entertainment exemption for judges when they are receiving personal hospitality.

"You could make the argument that sporting tickets count as entertainment," said Roth, whose group advocates for ethics reform and more transparency in the judiciary.

Thomas is not the only justice who has failed to report sporting event tickets on their disclosures. Justice Elena Kagan attended a University of Wisconsin football game -- sitting in the Chancellor's Box -- in 2017 that went unreported on her disclosure for that year, according to a Fix the Court review.

Still, ProPublica points to the example of 60 lower court judges who reported sporting event tickets on their annual forms between 2003 and 2019.

Invitations to a members-only golf club

It is a particularly complicated endeavor to decipher Thomas' reporting obligations for the access he reportedly got, via his friendship with Huizenga, to an exclusive Florida golf course. The report describes a "standing invitation" Thomas had to the members-only course, the Floridian, but ProPublica said it was not clear whether Thomas was granted a full-fledged membership or whether he was just able to visit the course as a guest of Huizenga.

However, there are signs pointing toward disclosure for judges who do receive gifted golf club memberships. In his filing for 2008, Chief Justice John Roberts reported honorary memberships to two golf courses -- valued in the thousands of dollars -- that he was gifted, while even noting in the disclosure forms that he didn't use the memberships.

"If that's John Roberts' interpretation of the federal disclosure law, I am going to side with him on this," Roth said.

Involvement in fundraising events

The latest investigation into Thomas' conduct also hit on an issue that has emerged around several of the justices: whether their activity with certain charities and other organizations violates ethical standards limiting judges' participation in fundraising.

ProPublica, piggybacking off recent reporting by The New York Times, dug into Thomas' involvement with the Horatio Alger Association, which offers scholarships and mentorships to students, and which connected Thomas to some of the billionaire benefactors highlighted in the report.

Thomas, according to The Times and ProPublica, facilitated events for the organization that were hosted at the Supreme Court, with the latest investigation reporting that access to one such event cost $1,500 or more in contributions per person.

Under a set of ethics rules for the judiciary that are separate from the financial disclosure requirements, judges are barred from allowing the "prestige" of their office to be used for the purpose of fundraising.

"You can attend an event of an organization, a non-profit that serves as a fundraiser," Gillers said. "But the justice or judge cannot be identified as an attraction for people to come and donate money."