A federal judge on Wednesday said she would grant bail to Kseniia Petrova, a Russian scientist employed by Harvard University, in an immigration case stemming from Ms. Petrova’s failure to declare scientific samples she was carrying into the country.

“There does not seem to be either a factual or legal basis for the immigration officer’s actions” in stripping Ms. Petrova of her visa on Feb. 16, Christina Reiss, chief judge of the U.S. District Court in Vermont, said in a court hearing.

She added that “Ms. Petrova’s life and well-being are in peril if she is deported to Russia,” as the government has said it intends to do.

While traveling to France on vacation, Ms. Petrova agreed to carry back samples of frog embryos from an affiliate laboratory at the request of her supervisor at Harvard Medical School.

When the samples were discovered during an inspection of Ms. Petrova’s baggage at Logan Airport in Boston, the customs official canceled her visa on the spot and started deportation proceedings. She was transferred to an Immigration and Customs Enforcement detention center in Louisiana, where she remained for more than three months.

At the end of the hearing on Wednesday, Judge Reiss said that “what happened in this case was extraordinary and novel,” and that if she did not take action in the case “there will be no determination” that Ms. Petrova’s rights had been violated.