A federal judge ruled Thursday that a former assistant to Roger Stone must testify before the grand jury convened by special counsel Robert Mueller.

As the Washington Post first reported, Chief Judge Beryl Howell rejected Andrew Miller’s challenge to Mueller’s subpoenas on the grounds that the entire special counsel investigation was unconstitutionally overbroad in its scope.

The ruling does not refer to Miller by name, but Miller’s attorney, Paul Kamenar, confirmed to the Post that it related to the request brought by his client.

“We’re disappointed with the court’s ruling,” Kamenar told the newspaper. “But the judge obviously took our challenge to Mueller’s constitutionality seriously as evidenced by the 93-page opinion.”

Howell’s ruling orders Miller, who served as a media liaison for Stone during the 2016 presidential campaign, to provide testimony as soon as possible and to turn over all subpoenaed records.

“The scope of the Special Counsel’s power falls well within the boundaries the Constitution permits, as the Special Counsel is supervised by an official who is himself accountable to the elected President,” Howell wrote.

In mid-July, TPM spotted attorneys from Mueller’s team and for Miller entering a closed-door hearing in Howell’s D.C. courtroom. The attorneys spent an hour and a half in the session.

Stone is under scrutiny in the special counsel investigation for his interactions with Guccifer 2.0, now known to be a group of Russian intelligence agents posing as a lone Romanian hacker. The self-proclaimed GOP dirty trickster also met with a Russian national during the campaign who asked for money in exchange for dirt on Hillary Clinton.

Stone has said he’s being unfairly targeted because of his closeness to Trump, a longtime friend.