A federal judge on Thursday found a veteran investigative reporter in contempt of court for failing to reveal her sources for stories she wrote about a scientist under investigation by the FBI.

Journalist Catherine Herridge, a former contributor to CBS News and Fox News, was sentenced to pay $800 a day until she divulged the information. Judge Christopher Cooper of the U.S. District Court in Washington stayed the fine for 30 days to give Herridge time to appeal.

The case, which has alarmed First Amendment advocates, involves a series of articles which were written by Ms. Herridge and her colleagues in 2017, while she was working at Fox News. The articles revealed that the FBI had investigated scientist Dr. Yanping Chen, a Chinese-American who is president of the University of Management and Technology in Arlington, Virginia, over suspicions of Chinese military ties and whether she had lied about American immigration . shapes.

The FBI ended its investigation without charging Dr. Chen, a year before Herridge and his colleagues published and broadcast their reports.

In 2018, Dr. Chen sued the FBI and other government agencies, accusing them of violating the Privacy Act by leaking information to Ms. Herridge. The Privacy Act protects personal information collected by federal agencies.

Judge Cooper ruled last year that Ms Herridge must reveal her confidential sources. On Thursday, he charged her with civil contempt for disobeying that order. He said she had not issued the order lightly, deciding that Dr. Chen’s need for information outweighed Ms. Herridge’s First Amendment protections.

“Herridge and many of his colleagues in the journalism community may disagree with that decision and prefer that a different balance be struck, but he is not permitted to disobey a federal court order with impunity,” Judge Cooper wrote in the ruling. from Thursday.

Patrick Philbin, Herridge’s attorney, said in an email: “We disagree with the district court’s decision and, to protect Herridge’s First Amendment rights, we intend to appeal.”

Herridge, who left Fox in 2019 to join CBS News as a senior investigative correspondent, was among nearly two dozen CBS News journalists who were laid off by the network this month.

Andrew C. Phillips, Dr. Chen’s attorney, said in a statement that without Privacy Act protections, federal authorities could “exploit their broad powers to invade the private life of an American citizen and then selectively leak documents to defame reputations or gain political points.”

“Today’s ruling is important to ensure that government officials can be held accountable for egregious abuses of power,” Mr. Phillips said.

A Fox News spokeswoman said that holding a journalist in contempt for protecting a confidential source “has a deeply chilling effect on journalism.”

“Fox News Media remains committed to protecting the rights of freedom of the press and expression and believes this decision should be appealed,” he said.

Gabe Rottman, chief counsel for the Reporters Committee for Freedom of the Press, said Thursday that while he disagreed with the ruling against Herridge, “it is a relief that Judge Cooper is allowing him to file an appeal without the financial pressure of fines.” daily.”

“The court’s opinion makes clear that the answer here has to be for Congress to pass a federal protective law,” Rottman said.