A three judge panel said Andrew Miller, who has been found in contempt of court for refusing to comply with a grand jury subpoena, did not prove that Mueller's appointment was illegal, as the judges said Rosenstein was legally vested with the power to appoint Mueller, with then Attorney General Jeff Sessions recused from the Russia investigation.

"The statutory and regulatory scheme demonstrate, contrary to Miller’s contention, that at the time of Special Counsel Mueller’s appointment, Acting Attorney General Rosenstein was the “Head of Department” under the Appointments Clause as to the matter on which the Attorney General was recused," the judges ruled in a 16 page opinion issued on Tuesday morning.