Kicking off the week on the radio Monday, LevinTV host Mark Levin raised a crucial point about the appointment of special counsel Robert Mueller that no one is currently discussing — it was unconstitutional.

"The appointment of Robert Mueller violates the United States Constitution," Levin said. "And every subpoena, indictment, and plea agreement should be null and void."

Listen:

Levin walked through the constitutional argument on the radio. He also summarized his argument in a note posted to Facebook:

"Every defendant, suspect, witness, etc., in this matter should challenge the Mueller appointment as a violation of the Appointments Clause," Levin wrote.