A federal judge recently ruled that investigative reporter Catherine Herridge must reveal her sources for an investigative series involving an FBI investigation into a Chinese scientist named Yanping Chen.

Herridge, currently with CBS News - but was was employed by Fox News at the time of the reports - must sit for a deposition and answer questions under oath about the identity and intent of her sources, per US District Judge Christopher Cooper.

"The Court recognizes both the vital importance of a free press and the critical role that confidential sources play in the work of investigative journalists like Herridge," wrote Cooper, and Obama appointee, in a 28-page ruling. "But applying the binding case law of this Circuit, the Court concludes that Chen's need for the requested evidence overcomes Herridge's qualified First Amendment privilege in this case."

Cooper's ruling has raised alarms with press freedom advocates, who argue that the ruling threatens the fundamental principle of journalists protecting their sources.

"Investigative journalism cannot function without credible assurances of confidentiality to sources," said Gabe Rottman, a director at the Reporters Committee for Freedom of the Press, in a statement to CNN. "While the Privacy Act provides essential protections for the public, using it to breach reporter-source confidentiality poses significant risks to a free press."

Legal representatives for Herridge and Fox News argued that the First Amendment shields journalists from such demands, and say that Chen's case didn't meet the criteria to violate this constitutional protection. They asserted that the public interest in safeguarding sources far outweighed the plaintiff's demand for information, which carried no broader societal significance.