No person may operate as a motor carrier or advertise or otherwise hold out as a motor carrier without a certificate or permit in effect. A certificate or permit may be suspended or revoked upon conviction of violating a provision of sections 221.011 to 221.296 or an order or rule of the commissioner or board governing the operation of motor carriers, and upon a finding by the court that the violation was willful. The board may, for good cause after a hearing, suspend or revoke a certificate or permit for a violation of a provision of sections 221.011 to 221.296 or an order issued or rule adopted by the commissioner or board under this chapter.