WASHINGTON — Conservative Supreme Court Justice Samuel Alito could barely contain himself Thursday after liberal Justice Sonia Sotomayor opted to read her full dissent in an immigration case from the bench, a rare rebuke of her colleagues.

Alito began by briefly summing up his majority opinion in Mullin v. Al Otro Lado, in which he held that the government has the right to turn back migrants stopped at the US border before giving them a chance to apply for asylum.

As Sotomayor read her 35-page dissent, Alito — never known for his poker face — began rocking back and forth in his chair before leaning forward, propping his chin in his hands and staring at the ceiling while his colleague described the majority opinion as “egregiously wrong,” according to The Hill.

After Sotomayor finished, a scowling Alito tersely said that had he known she would deliver her dissent in full, “there’s much more I would have added” to his own comments.

The George W. Bush appointee urged those present to go through his full opinion to see how he responded to Sotomayor’s dissent, then pointed out that the policy in question had been used by a Democratic and a Republican presidential administration before restraining himself from commenting further, saying: “I won’t add anything more to that.”

It is very unusual for justices to snipe at each other from the bench or add commentary when delivering opinions. Past and current members of the court who hold opposing points of view have emphasized their strong personal and professional relationships, helping to elevate the public perception of the judiciary.

It was not immediately clear whether Sotomayor breached Supreme Court etiquette by not giving a heads-up that she would read her dissent, which is typically done to demonstrate strong objections to a decision.

On the final day of the Supreme Court’s 2024-25 term, Sotomayor read two dissents from the bench — one in a case limiting the use of nationwide injunctions to halt executive actions, and the other in opposition to allowing parents in a Maryland school district to opt their kids out of lessons with LGBTQ-themed books.

“The consequences of today’s decision are predictable,” Sotomayor had written Thursday. “More people will die.”

“More people will turn back and be subjected to violence because of something they cannot or should not have to change about themselves, such as their race, religion, nationality, or political opinion.”

Alito authored three of the four majority opinions issued by the high court Thursday and summarized them back-to-back.

In a separate ruling, Alito found that the Trump administration could yank Temporary Protected Status for migrants from Haiti and Syria, ending their immunity from deportation.

In Mullin v. Al Otro Lado, the court ruled that the practice of “metering,” which caps the number of people who can apply for asylum each day, was legal under federal law which allows migrants to seek protection once on American soil, regardless of whether they entered the US legally.