Maryland Code, Transportation § 14-103

(a) No person, except a person while making lawful use of it in pursuit of a legitimate business interest or a law enforcement officer while in pursuit of his duties, shall at any time have or possess a motor vehicle master key adapted for or capable of being used to open any motor vehicle in this State.

(b) No person, except a person while making lawful use of a motor vehicle master key in pursuit of a legitimate business interest or a law enforcement officer while in pursuit of the law enforcement officer's duties, shall at any time have or possess a motor vehicle master key adapted for or capable of being used to operate any motor vehicle in this State.

(c) A person convicted of a violation of this section is subject to imprisonment not exceeding 1 year or a fine not exceeding $500 or both.