WASHINGTON — Justice Samuel Alito took the unusual step late Tuesday of responding to questions about his travel with a billionaire who frequently has cases before the Supreme Court hours before an article detailing their ties had even been published.

In an extraordinary salvo in a favored forum, Alito defended himself in a preemptive article in the opinion pages of The Wall Street Journal before the news organization ProPublica posted its account of a luxury fishing trip in 2008.

His response comes as the justices face mounting scrutiny over their ethical obligations to report gifts and to recuse themselves from cases involving benefactors.

The justices have taken differing approaches to explaining their actions and attempting to protect their institution. Justice Clarence Thomas has been largely silent in the face of revelations of gifts from Harlan Crow, a wealthy Republican donor. Chief Justice John Roberts turned down an invitation in April to testify about the court’s ethics practices before the Senate Judiciary Committee and made vague statements about addressing them.

And Alito has come out swinging.

The ProPublica article centered on a trip Alito took to a remote part of Alaska, arriving on the private jet of Paul Singer, a wealthy hedge fund manager and Republican donor. The flight would have cost more than $100,000 one way if Alito had chartered it himself, the outlet estimated, and his annual disclosures make no mention of the trip. Over the years after the trip, Singer’s businesses were parties to a number of Supreme Court cases in which Alito participated.

Alito’s three-day stay at the King Salmon Lodge was paid for by another wealthy donor, Robin Arkley, the owner of a mortgage company then based in California.

Leonard Leo, then a leader of the Federalist Society conservative legal group, helped make arrangements for the trip, including securing a spot for Alito aboard Singer’s jet.

ProPublica had sought comment from the justice, who instead turned to the Journal to make two main points: that he was not required to recuse himself from cases in which Singer had an interest or to disclose the travel on his private jet.

Alito said he had spoken to Singer no more than a handful of times, including on two occasions when Singer introduced the justice before speeches. “It was and is my judgment that these facts would not cause a reasonable and unbiased person to doubt my ability to decide the matters in question impartially,” Alito wrote.

He added that he did not know of Singer’s connection to the cases before the court, including one in which the court issued a 7-1 decision in favor of one of Singer’s businesses, with Alito in the majority.

But Singer’s connection to the case, Republic of Argentina v. NML Capital, was widely reported. A Forbes article covering the decision bore the headline “Supreme Court Hands Billionaire Paul Singer a Victory Over Argentina.” An article in The New York Times noted that the parties to the case included “NML Capital, an affiliate of Elliott Management, the hedge fund founded by Paul Singer.”

Alito said he was not required to disclose the trip on Singer’s private jet in “a seat that, as far as I am aware, would have otherwise been vacant.”

A federal law requires disclosures of gifts over a certain value but makes exceptions for “personal hospitality of any individual” at “the personal residence of that individual or his family or on property or facilities owned by that individual or his family.” Alito wrote that a jet is such a facility, quoting from dictionary definitions.

The Judicial Conference of the United States, the policymaking body for the federal courts, had recently issued new guidelines requiring disclosure of travel by private jet and stays in commercial properties like resorts.

After ProPublica disclosed that Thomas had taken luxury trips paid for by Crow, the justice said he would comply with the new guidelines. Thomas justified accepting the trips because of what he said was his close friendship with Crow.

A picture from the Alaska trip published by ProPublica shows Alito in hip waders with a fishing guide, posing with a massive king salmon.

At night, the group dined on king crab legs or Kobe beef. One member of the group boasted that the wine they were drinking cost $1,000 a bottle, one of the lodge’s fishing guides told ProPublica.

Alito disputed the notion that the trip was particularly fancy. “I stayed for three nights in a modest one-room unit at the King Salmon Lodge, which was a comfortable but rustic facility,” he wrote. “As I recall, the meals were home-style fare. I cannot recall whether the group at the lodge, about 20 people, was served wine, but if there was wine it was certainly not wine that costs $1,000.”

In a statement to ProPublica, Leo wrote that justices across the ideological spectrum had received similar hospitality from their own allies and that their judicial work had been unaffected.

“We all should wonder whether this recent rash of ProPublica stories questioning the integrity of only conservative Supreme Court justices is bait for reeling in more dark money from woke billionaires who want to damage this Supreme Court and remake it into one that will disregard the law by rubber stamping their disordered and highly unpopular cultural preferences,” Leo said.

Associated Press contributed.