SAN FRANCISCO — Glassdoor Inc., the operator of the anonymous online job review site, has asked the U.S. Court of Appeals for the Ninth Circuit to block an attempt by federal prosecutors to unmask reviewers as part of a grand jury investigation.

In a case unsealed on Tuesday, Glassdoor was ordered by U.S. District Judge Diane Humetewa for the District of Arizona to divulge the identities of eight people who posted anonymous reviewers about a federal contractor under investigation for fraud.

Glassdoor has refused to comply with the order, arguing on the reviewers’ behalf that they have a First Amendment right to speak anonymously and to associate freely on the online platform. The company filed its sealed notice of appeal from a contempt order on June 7.

In a blog post on Friday, Glassdoor general counsel Brad Serwin wrote the district court “applied the wrong standard in placing the interests of government ahead of Americans’ protected free speech rights under the First Amendment.” He added: “We hope to persuade the U.S. Ninth Circuit Court of Appeals to require a higher standard for these requests.”

Glassdoor is being represented in the litigation by Todd Hinnen, a Perkins Coie litigator in Seattle who previously served as acting assistant attorney general for national security at the U.S. Department of Justice. Hinnen has also represented companies such as Google Inc. in fighting warrants for user data in areas where the law is murky.

Glassdoor has dealt with civil cases before where companies have sought to learn the identities of commenters, and has been largely successful in shutting them down. A federal magistrate judge in San Francisco last year denied an attempt by an Illinois office design and supply firm to unmask negative commenters, citing the chilling effect that would have on protected speech.

In the Arizona case, Glassdoor has argued that prosecutors cannot use a grand jury subpoena to expose the identities of anonymous commenters unless they show a clear connection between their investigation and the information they are seeking.

Prosecutors originally sought to identify 125 reviewers, but later narrowed their request to just eight after Glassdoor pushed back. The name of the contractor subject to the investigation is redacted in court documents, but The Wall Street Journal in a report Friday identified the company as TriWest Healthcare Alliance, a Phoenix-based company that administers federal veteran benefits.

Both Glassdoor and the Department of Justice are drawing largely on law that involves a much older type of media: newspapers.

The case that the DOJ appears to believe weighs most strongly in its favor is a 1972 decision by the U.S. Supreme Court called Branzburg v. Hayes, involving three reporters who sought to protect the identity of their sources. The court ruled that the First Amendment did not shield them from having to respond to a grand jury subpoena.

Glassdoor argues Branzburg does not apply to the facts of its case. But it also cites a ruling around the same time by the Ninth Circuit, Bursey v. United States, involving reporters for the Black Panthers Newspaper. It argues that that case supports its contention that prosecutors must show the information they are seeking is relevant in order to overcome First Amendment protections.

That argument, however, rests somewhat on the notion that the protected speech is somehow political in nature. Judge Humetewa agreed with the government that Bursey is not a good fit for Glassdoor’s situation.

“Glassdoor’s users are not a political association, nor are they engaged in the type of advocacy at issue in Bursey,” she wrote. “The fact that the relevant users in this case work (or worked) for a publicly-funded program does not make this speech political.”

Dominic Lanza, a spokesman for the U.S. Attorney’s Office in Phoenix, declined to comment on the case.

Ben Hancock is a San Francisco-based reporter for The Recorder and Law.com. He writes about the future of litigation, including third-party finance, legal data analytics, and artificial intelligence in the law. Contact Ben at bhancock@alm.com. On Twitter: @benghancock.