325A.23  Suspension or revocation of permit or certificate.
  The department may, in addition to other penalties, revoke or suspend the permit or certificate of a motor carrier for a violation of this chapter or a rule adopted under this chapter. For flagrant or persistent violations of safety or hazardous materials rules by the holder of a permit or certificate or the holder’s agent, the department may suspend the permit or certificate of necessity until the rules adopted by the department are complied with, or the department may revoke the permit or certificate for continued noncompliance.
97 Acts, ch 104, §54, 61