Maryland Transportation Section 21-903
(a)   (1)   In this section the following words have the meanings indicated.
(2)   "Alcoholic beverage" means a spirituous, vinous, malt, or fermented liquor, liquid, or compound that contains at least 0.5% alcohol by volume and is fit for beverage purposes.
(3)   (i)   "Passenger area" means an area that:
1.   Is designed to seat the driver and any passenger of a motor vehicle while the motor vehicle is in operation; or
2.   Is readily accessible to the driver or a passenger of a motor vehicle while in their seating positions.
(ii)   "Passenger area" does not include:
1.   A locked glove compartment;
2.   The trunk of a motor vehicle; or
3.   If a motor vehicle is not equipped with a trunk, the area behind the rearmost upright seat or an area that is not normally occupied by the driver or a passenger of the motor vehicle.
(b)   This section applies to a motor vehicle that is driven, stopped, standing, or otherwise located on a highway.
(c)   A driver of a motor vehicle may not consume an alcoholic beverage in a passenger area of a motor vehicle on a highway.
(d)   Notwithstanding Article 2B, Title 19 of the Code or any other provision of law, the prohibition contained in this section applies throughout the State.