Maryland Transportation Section 23-403

      (a)      The operation of a diesel vehicle on any highway in this State constitutes the consent of the driver and owner of the diesel vehicle to be subject to an emissions test established under this subtitle.

      (b)      The driver of a diesel vehicle shall obey any sign or direction of a police officer to stop the diesel vehicle and submit it to an emissions test administered by an emissions inspector:

            (1)      When a diesel vehicle is required to submit to:

                  (i)      Weighing and measuring under § 24-111 of this article; or

                  (ii)      A motor carrier safety inspection under § 25-111 of this article; or

            (2)      At any location or time, when a police officer has reasonable cause to believe that an individual diesel vehicle is violating emissions standards established under this subtitle.