“Mr. Scalia,” Chief Justice John Roberts called out at Supreme Court oral arguments Tuesday.

Though “Justice Scalia” is still often invoked in the courtroom, this time, Roberts indeed meant the late conservative justice’s son, Eugene Scalia, who then started at the lectern.

“Thank you, Mr. Chief Justice, and may it please the court,” he began, Scalia’s debut argument in the courtroom where his father, Antonin Scalia, served for nearly 30 years.

A longtime employment lawyer who served as Department of Labor secretary under former President Trump, Scalia now works as a partner at Gibson, Dunn & Crutcher, where he is also co-chairman of the firm’s administrative law and regulatory practice group.  

On Tuesday, Scalia was representing investment bank UBS Securities as it fights a corporate whistleblower lawsuit at the high court.

Watching from the side of the courtroom was Maureen Scalia, Eugene’s mother and the late justice’s widow.                                    

Tuesday’s case arose after a jury sided with Trevor Murray, a former UBS research strategist who said he was fired after complaining that the trade desk was pressuring him to skew his reports about the company’s commercial mortgage-backed securities. 

Murray brought his lawsuit under the Sarbanes-Oxley Act, which Congress passed in the wake of the Enron scandal to protect investors and crack down on corporate wrongdoing.

At issue is whether the complicated legal framework that governs the act’s whistleblower protections required Murray to show to a jury that the company acted with retaliatory intent in firing him. 

On behalf of UBS, Scalia is arguing retaliatory intent is required, so the jury’s verdict can’t be upheld.

“In Sarbanes-Oxley, Congress employed a phrase, ‘discriminate because of,’ that has long been recognized to require a plaintiff to show discriminatory intent. It is this transplanted phrase with its rich soil that decides this case,” Scalia said in his opening to the justices, five of whom served with his father. 

One of them, Justice Elena Kagan, looked out in Eugene Scalia’s direction when she first entered the courtroom to take her seat, raising her eyebrows and appearing to give a slight nod.

Kagan has spoken publicly about her bond with Justice Scalia and how the duo went on hunting trips together after Kagan arrived at the court in 2010.

Despite any history, during the argument the justices made no reference to the late justice or the familial relationship. Kagan and other justices posed piercing questions to Scalia about the case and the nuanced burden-shifting framework between whistleblowers and employers that is at issue in the lawsuit.

“I don’t understand that, Mr. Scalia,” Kagan pushed back at one point.

Gibson, Dunn & Crutcher is no stranger to the Supreme Court, with its lawyers having argued nearly 160 cases there, according to the firm’s website.

The firm years ago also employed Philip Alito, the son of current Justice Samuel Alito, while his father served on the bench.

Scalia worked at the firm prior to being in Trump’s Cabinet, including while his father was on the high court, though he never previously argued a Supreme Court case.

Bloomberg reported that the firm had a setup at the time so that Scalia would not benefit financially from the firm’s Supreme Court advocacy work.

“I’m grateful to have been given the privilege of arguing this important employment case, and of appearing before the Court that meant so much to my father,” Scalia told The Hill in a statement.