Government lawyers told a federal judge on Wednesday that the Trump administration intends to deport a Harvard scientist back to Russia, a country she fled in 2022, despite her fear that she will be arrested there over her protest of Russia’s war in Ukraine.

Kseniia Petrova, a researcher at Harvard Medical School, has been held in a Louisiana immigration detention facility since February, when she was detained at Boston’s airport for failing to declare scientific samples she was carrying in her luggage.

This is the first time the government has formally stated its plan to deport her to Russia.

In Wednesday’s hearing, Christina Reiss, chief judge of the United States District Court in Vermont, quizzed the government lawyers about their grounds for canceling Ms. Petrova’s visa and detaining her. Judge Reiss went on to schedule a bail hearing on May 28, potentially setting the stage for Ms. Petrova’s release.

The case has drawn the attention of elite scientists around the world, and sent a chill though the community of international academics that surrounded Ms. Petrova at Harvard. Several dozen Harvard students and faculty made the drive to Burlington, Vt., for the hearing.

“For every person that they detain, thousands of others are going to be scared of coming to the country,” said Leo Gerdén, a Harvard senior from Sweden.

Ms. Petrova was detained at Logan Airport on Feb. 16 as she returned from vacation in France, carrying with her sections of frog embryos from an affiliate laboratory, at the request of her supervisor at Harvard.

She has admitted that she failed to declare the samples, but her lawyer has argued that this would ordinarily be treated as a minor infraction, punishable with a fine. Instead, the customs official canceled Ms. Petrova’s J-1 visa on the spot and initiated deportation proceedings.

When Ms. Petrova explained that she had fled her native Russia for political reasons and could not return there, she was processed as an asylum seeker, and sent to Richwood Correctional Center in Monroe, La., where she has remained for nearly three months.

In remarks from the bench, Judge Reiss seemed skeptical that the airport customs agent had possessed the authority to cancel Ms. Petrova’s visa.

“Where is that authority?” she asked. “Where does a customs and border patrol officer have the authority on his or her own to revoke a visa?” she said. “It’s got to be somewhere. Because there is no way that person has kind of an unlimited determination.”

The judge noted that the she had reviewed the statute laying out the grounds for customs officers to find someone inadmissible to the United States, and “I don’t see anything about customs violations.”

Jeffrey M. Hartman, an attorney representing the Department of Justice, said “it’s the secretary of state’s authority” to cancel a visa, and that the secretary has delegated that authority to customs officials.

Judge Reiss asked the government to clarify whether or not it planned to deport Ms. Petrova to Russia.

“You are asking for her removal to Russia?” she asked.

“Yes, your honor,” Mr. Hartman replied.

Ms. Petrova’s attorney filed a petition challenging her detention with the federal court in February, when she was held briefly at a Vermont detention center before being transferred to the immigration detention center in Louisiana.

Mr. Hartman argued that the federal court had no jurisdiction over Ms. Petrova’s detention. He said Ms. Petrova may contest her detention, but only in a Louisiana immigration court.

“It’s not something that a district court can entertain,” he said. “We think the proper venue for that question is Louisiana, where she is detained and where her custodian is.”

“But she is only detained there because you moved her,” said the judge.

Mr. Hartman said that when Ms. Petrova had been asked whether she was carrying biological materials, that she “failed to disclose their full contents,” and was carrying “a baggie with loose vials of this experimental material.”

“The C.B.P. office was our first line of defense against unknown biological materials from a foreign national out of a port of entry,” he said.

Over the past few weeks, federal courts in Vermont have handed down a series of decisions favoring noncitizen academics caught up in President Trump’s immigration crackdown.

On May 9, Tufts doctoral student Rumeysa Ozturk was released from detention on the orders of a judge, William K. Sessions III, who said that her continued detention could chill “the speech of the millions and millions of individuals in this country who are not citizens.”

And on April 30, Judge Geoffrey W. Crawford ordered the release of Mohsen Mahdawi, a student organizer at Columbia University who was detained by immigration authorities during an interview for his naturalization. Both Ms. Ozturk and Mr. Mahdawi were singled out because they had vocally protested Israel’s military campaign in Gaza.

Ms. Petrova’s case has no apparent basis in any political activism. But the attorney general of Massachusetts, Andrea Joy Campbell, who filed an amicus brief in the case, said Ms. Petrova’s detention, like that of Ms. Ozturk, represented “reckless and cruel misuse of power to punish and terrorize noncitizen members of the academic community.”

Ms. Campbell argued that international students bring significant revenue into Massachusetts, and that by creating “an atmosphere of fear,” the Trump administration has threatened the state’s economy.

Ms. Petrova’s attorney, Gregory Romanovsky, has argued that customs officials overstepped their authority by revoking her visa.

Though Customs officials may, in some cases, determine that an individual is inadmissible, he said, they must identify the legal grounds for doing so, such as criminal activity or health concerns. He said failing to declare scientific samples did not meet that test.

“It shouldn’t make her any more inadmissible than cutting in front of the line when she was waiting to be inspected,” Mr. Romanovsky said. “What the government is doing is saying, ‘If you’re an immigrant or a noncitizen and you’re not on your best behavior, we will punish you. We are going to use various immigration provisions to get rid of you.’ ”

Adam Sychla, a postdoctoral research fellow who organized a group of roughly 20 Harvard students and faculty members who traveled from Cambridge to the courthouse in Burlington, Vt., said he had never met Ms. Petrova, but had immediately decided to make the drive.

“Whether I know her personally or not, is immaterial,” he added. “I easily could have met her last week to start a collaboration. Instead, Kseniia is being unfairly detained.”

Miles J. Herszenhorn contributed reporting from Cambridge, Mass.