Billionaire Leon Black was scheduled to testify about his dealings with convicted sex offender Jeffrey Epstein under a subpoena from the House Oversight Committee on Thursday morning. But instead of appearing, Black filed a lawsuit against the committee and its Republican chairman, accusing them of overstepping their authority.

His civil lawsuit describes the House panel’s inquiry — led by Rep. James Comer, R-Ky. — as a “public fishing expedition,” accusing its members of attempting to score political points.

In response, Comer called Black’s actions “unacceptable” and said he and other panel members would discuss whether to hold Black in contempt.

“I don’t think I need to tell anyone in here how important of a witness Mr. Black is to this investigation,” Comer told journalists on Capitol Hill. He added that of all the powerful people interviewed by the panel, Black is the first to file a lawsuit.

Black, founder of the Apollo Global Management private equity firm, is one of several prominent figures the panel has sought to hear from as it probes the scope of Epstein’s ties. His name appears in the Justice Department’s Epstein files thousands of times. Appearing in the files is not necessarily an indication of criminal wrongdoing.

The federal suit filed in the U.S. District Court for the District of Columbia argues that the House committee’s authority is limited by a requirement that its actions serve a “legitimate legislative purpose.” And in this case, Black’s lawsuit states, the panel has overstepped those bounds.

Black previously spoke to the House Oversight Committee in June. But he ended that voluntary appearance after Comer raised the subject of nondisclosure agreements, according to Black’s lawsuit.

Now he’s refusing to comply with the House committee’s subpoena seeking any nondisclosure agreements to which he might be a party. Black says he has already “produced the only confidentiality agreement in which Epstein could have been ‘involved’ because it is the only one executed while he was alive,” according to the suit.

Epstein was arrested in July 2019 on federal sex-trafficking charges and later died in prison. Authorities determined his death was a suicide.

Producing NDAs sought by one of the subpoenas, Black says, would lead to “the disclosure of the unredacted identities and private circumstances of women who bargained for confidentiality.”