Two well-known lawyers, including White House counselor Kellyanne Conway’s husband, argued Thursday that the appointment of Matthew Whitaker, former chief of staff to ousted Attorney General Jeff Sessions, as acting attorney general was unconstitutional.

In a New York Times op-ed, George Conway and former Acting Solicitor General Neal Katyal argued that because Whitaker has never been confirmed by the Senate, his appointment is “illegal” and “anything Mr. Whitaker does, or tries to do, in that position is invalid.”

“Constitutionally, Matthew Whitaker is a nobody,” the op-ed states. “Mr. Whitaker’s installation makes a mockery of our Constitution and our founders’ ideals.”

Many have pointed out that the fact that Sessions technically resigned from his position — as opposed to being fired — allows Whitaker to act as his replacement on a temporary basis. Conway and Katyal noted the discussion about the Vacancies Reform Act but argued that Whitaker’s appointment still runs afoul of the Constitution.

They wrote that the move violate’s the Constitution’s Appointment Clause.

“Because Mr. Whitaker has not undergone the process of Senate confirmation, there has been no mechanism for scrutinizing whether he has the character and ability to evenhandedly enforce the law in such a position of grave responsibility,” they wrote.

“The public is entitled to that assurance, especially since Mr. Whitaker’s only supervisor is President Trump himself, and the president is hopelessly compromised by the Mueller investigation,” they continued. “That is why adherence to the requirements of the Appointments Clause is so important here, and always.”

Conway, though married to a prominent Trump administration staffer, Kellyanne Conway, has made a name for himself as a loud and frequent critic of the President.