WASHINGTON — A clash between judges on two important federal courts in Washington has created an early, unusual test of new rules intended to make sure courthouses across the country are civil, harassment-free workplaces.

And it’s exposed the perils of the reply-all email, even among judges-for-life.

An exchange about a climate change seminar for judges set off the controversy, after a two-sentence-long heads-up message about the session — co-sponsored by the research and education agency of the judiciary, the Federal Judicial Center — was sent.

One judge’s share about the event provoked a pushback email from a colleague, who questioned the judge’s ethics and climate change science, and urged the judge to stick to his lane on what “you are being paid to do” — adding that “the jurisdiction assigned to you does not include saving the planet.”

The correspondence that went to 45 judges and the staff members who monitor their email accounts was obtained and confirmed by The Washington Post and is an uncommon exposure of private conversations among the usually discreet federal bench.

It also poses the question about how the judiciary now will police itself.

The federal judge who flagged the event, U.S. District Judge Emmet G. Sullivan, on Aug. 1 asked the judiciary’s committee that oversees judges’ conduct to deliver an opinion about whether the brusque reply-all from senior appeals court Judge A. Raymond Randolph was a violation and/or a reason for Randolph to recuse himself from certain cases.

“This is really remarkable. The public doesn’t get to listen in on the manner in which judges talk to each other in private discussions,” Stephen Gillers, a professor at New York University Law School and a judicial ethics expert, said after being told about the emails The Post acquired.

Sullivan and Randolph, who both are in their 70s and have spent decades on the bench, declined to comment on the confidential inquiry.

The controversy began the evening of July 3, when Sullivan forwarded the invitation as “just FYI.”

Less than an hour later, Randolph, who serves on the U.S. Court of Appeals for the D.C. Circuit, replied all. He chided Sullivan for “subjecting our colleagues to this nonsense” and suggested he had crossed an ethical line. He asked: “Should I report you? I don’t know.”

“The jurisdiction assigned to you does not include saving the planet. A little hubris [sic] would be welcomed in many of your latest public displays,” Randolph wrote.

“The supposedly science and stuff you are now sponsoring is nothing of the sort,” his email continued. “Get out of this business and back into the business of judging, which are what you are being paid to do.”

Sullivan quickly responded, copying all, and promised to delete the appellate judge from further missives: “I sincerely regret that you were offended by my email! I merely forwarded an email announcing a seminar sponsored in conjunction with the support of the Federal Judicial Center. I have no stake in that seminar,” Sullivan wrote.

Two other judges then weighed in, defending Sullivan.

One called Randolph’s tone “accusatory” and “quite disturbing” and another explained the purpose of the seminar and noted that a board chaired by Chief Justice John Roberts had blessed the event.

More than two weeks after his initial note, Randolph again addressed the email list. After learning more about the Environmental Law Institute’s program and the judiciary’s co-sponsorship, he wrote: “While I continue to disagree with their conclusion about the propriety of the program, I think their position is fairly held.”

Given that, he wrote, “I do not believe that Judge Sullivan acted improperly in circulating the invitation to ELI’s program.”

Randolph said in an interview this week that his initial message and strong language “was a mistake.” He inadvertently replied to the entire email loop, he said, and has no ill will or animosity toward Sullivan. “That goes without saying,” Randolph said.

Gillers of NYU said Randolph “acted impetuously and inappropriately” and displayed a “lack of judicial temperament. Sullivan did absolutely nothing wrong” in forwarding the invitation.

After his initial email, Randolph followed up with a four-page memo to another colleague, in which he expanded on his concerns about the seminar, which was described in the invitation as “neutral, objective information.”

Randolph viewed it differently saying in his memo that judges attending a climate science program put on by the Environmental Law Institute lends “credence to one side of the climate change debate that is quite improper” because of a host of litigation on the issue.

Experts on judicial ethics said the appeals court judge should have issued a direct apology to Sullivan and they suggested Randolph recuse himself from cases involving climate change.

As of Tuesday morning, Randolph was listed as one of three judges to hear arguments Sept. 6 in a case brought by California and more than a dozen other states challenging an Environmental Protection Agency decision to scrap some vehicle emissions standards.

Just before 5 p.m. Tuesday, the court calendar was updated and Randolph’s name was replaced. The clerk’s office and Randolph declined to comment on the change.

Gillers and Arthur D. Hellman of the University of Pittsburgh law school said in interviews that the strong views Randolph expressed suggest he should not sit on cases related to global warming. A judge is entitled to opinions as long as those views remain private. But Randolph’s commentary about climate science “would give litigants reason to doubt his impartiality,” Hellman said.

The back-and-forth between the judges comes after the federal judiciary in March adopted a new system for handling workplace harassment complaints.

Ethics professors, law clerks and advocates of court transparency had pressed for more disclosure and accountability for judges following sexual misconduct claims against a once prominent appeals court judge in California, Alex Kozinski.

The judiciary’s new rules specifically call for judges to “practice civility, by being patient, dignified, respectful, and courteous, in dealings with court personnel” and say a judge should not engage in “abusive behavior.”

Hellman said Randolph’s behavior “does raise a question as to whether he has violated that norm” particularly when “something is circulated this widely within the court family.”

Sullivan was nominated in 1994 by President Bill Clinton after serving as a judge in D.C. Superior Court and the D.C. Court of Appeals. He is perhaps best known for throwing out the guilty verdict in the 2008 corruption case against the late Alaska Sen. Ted Stevens after the Justice Department revealed that prosecutors kept key information from defense attorneys.

Among his current assignments, Sullivan is presiding over the criminal prosecution of former Trump national security adviser Michael Flynn and the lawsuit filed by congressional Democrats alleging the president’s private business violates the anti-corruption “emoluments” provisions of the Constitution.

Randolph, who took senior status and a reduced workload in 2008, was nominated to the bench by President George H.W. Bush in 1990. He is a former deputy solicitor general, who argued 23 Supreme Court cases, and a former chairman of the judiciary’s ethics committee. At his portrait presentation ceremony in 2012, colleagues described Randolph’s sharp, direct dissents written “like John Wayne speaks” and how the former college wrestler deftly challenges lawyers at oral argument.

After the email exchanges in July, Sullivan turned to the judiciary’s Committee on Codes of Conduct for advice, requesting an advisory opinion.

Sullivan in a letter asked whether Randolph’s characterization of the climate seminar as “nonsense” and “supposedly science” mean that his impartiality is impaired.

And, he asked, does a reference Randolph made to Sullivan’s “latest public displays” suggest Randolph should recuse himself from appeals involving Sullivan’s orders.

The chairman of the conduct committee, Judge Ralph R. Erickson of the U.S. Court of Appeals for the 6th Circuit, and a spokesman for the Administrative Office of the U.S. Courts declined to comment.

Gillers said the judiciary’s committee is unlikely to respond with an opinion, as Sullivan seeks, because the panel of fellow judges “does not want to be caught up in a contretemps between Sullivan and Randolph.”

In general, the committee provides guidance to judges about potential conflicts of interest — not about the behavior of other judges. Opinions issued by the panel are confidential unless a judge chooses to release it publicly.