The scientist who claimed that comments on the postpublication peer-review website PubPeer caused him to lose a job offer has now filed suit against the anonymous posters and has subpoenaed the website’s operators in a bid to obtain their identities.

In September, PubPeer’s anonymous moderators revealed that Fazlul Sarkar, a cancer researcher at Wayne State University in Detroit, Michigan, had threatened legal action after the University of Mississippi rescinded its offer of a tenured, $350,000-per-year position. Sarkar, who remains employed at Wayne State, claimed that anonymous comments suggesting misconduct in his research caused the university to revoke its offer.

This weekend, PubPeer moderators announced in a comment thread that Sarkar has filed a libel suit in a Wayne County circuit court against several “John Does” behind the comments he considers defamatory. And although he is not suing PubPeer directly, Sarkar has filed a subpoena asking the site’s moderators to turn over “all identifying information” about the posters by 10 November. As a Retraction Watch post on the suit explains, shield laws in many states would likely have protected PubPeer from being forced to turn over whatever information it has about the commenters, but Michigan’s shield law applies only to grand jury and criminal cases, not civil cases like this one.

In an associated complaint letter, Sarkar’s lawyer, Nicholas Roumel of Nacht, Roumel, Salvatore, Blanchard & Walker, P.C. in Ann Arbor, Michigan, details the specific comments he considers defamatory. He also quotes a 19 June letter from Larry Walker, the director of the National Center for Natural Products Research at the University of Mississippi Cancer Institute, where Sarkar was to hold an appointment. In the letter, Walker cites the PubPeer comments as the reason for reversing the university’s job offer, explaining that “to move forward would jeopardize our research enterprise and my own credibility.”

PubPeer moderators previously told ScienceInsider in an e-mail that they intend to protect their users’ identities, and lawyers at the American Civil Liberties Union (ACLU) in New York City have offered to help the defend PubPeer against a subpoena. The moderators have not yet announced how they plan to respond.