Maryland Code, Criminal Law § 10-125

(a)(1) Except as otherwise provided in subsection (c) of this section, an occupant of a motor vehicle may not possess an open container that contains any amount of an alcoholic beverage in a passenger area of a motor vehicle on a highway.

(2) A driver of a motor vehicle may not be subject to prosecution for a violation of this subsection based solely on possession of an open container that contains any amount of an alcoholic beverage by another occupant of the motor vehicle.

(b)(1) This subsection does not apply to the driver of a motor vehicle.

(2) Except as otherwise provided in subsection (c) of this section, an occupant of a motor vehicle may not consume an alcoholic beverage in a passenger area of a motor vehicle on a highway.

(3) An occupant of a motor vehicle may not smoke cannabis in a passenger area of a motor vehicle on a highway.

(1) a motor vehicle designed, maintained, and used primarily for the transportation of a person for compensation, including:

(2) the living quarters of a motor home, motor coach, or recreational vehicle.

(1) a moving violation for the purposes of § 16-402 of the Transportation Article; or

(2) a traffic violation for the purposes of the Maryland Vehicle Law.