A prominent former Consumer Financial Protection Bureau official is resisting a deposition by Navient Corp. in a student loan lawsuit, arguing that the questioning would require him to discuss confidential information and amount to an “open-ended fishing expedition.”

Seth Frotman, the CFPB’s former student loan ombudsman, filed papers in Pennsylvania federal court late Tuesday to block a subpoena issued by Delaware-based Navient, one of the country’s largest student loan servicing companies. Frotman resigned from the bureau in August in protest of its Trump-appointed leadership.