Md. Code, Pub. Safety § 5-134

(a) This section supersedes any restriction that a local jurisdiction in the State imposes on the transfer by a private party of a regulated firearm, and the State preempts the right of any local jurisdiction to regulate the transfer of a regulated firearm. (b) A dealer or other person may not sell, rent, loan, or transfer a regulated firearm to a purchaser, lessee, borrower, or transferee who the dealer or other person knows or has reasonable cause to believe: (1) is under the age of 21 years, unless the regulated firearm is loaned to a borrower who may possess the regulated firearm under § 5–133(d) of this subtitle; (2) has been convicted of a disqualifying crime; (3) has been convicted of a conspiracy to commit a felony; (4) has been convicted of a violation classified as a common law crime and received a term of imprisonment of more than 2 years; (5) is a fugitive from justice; (6) is a habitual drunkard; (7) is addicted to a controlled dangerous substance or is a habitual user; (8) suffers from a mental disorder as defined in § 10–101(i)(2) of the Health – General Article, and has a history of violent behavior against the purchaser, lessee, borrower, or transferee or another, unless the purchaser, lessee, borrower, or transferee possesses a physician’s certificate that the recipient is capable of possessing a regulated firearm without undue danger to the purchaser, lessee, borrower, or transferee or to another; (9) has been confined for more than 30 consecutive days to a facility as defined in § 10–101 of the Health – General Article, unless the purchaser, lessee, borrower, or transferee possesses a physician’s certificate that the recipient is capable of possessing a regulated firearm without undue danger to the purchaser, lessee, borrower, or transferee or to another; (10) is a respondent against whom a current non ex parte civil protective order has been entered under § 4–506 of the Family Law Article; (11) if under the age of 30 years at the time of the transaction, has been adjudicated delinquent by a juvenile court for an act that would be a disqualifying crime if committed by an adult; (12) is visibly under the influence of alcohol or drugs; (13) is a participant in a straw purchase; (14) subject to subsection (c) of this section for a transaction under this subsection that is made on or after January 1, 2002, has not completed a certified firearms safety training course conducted free of charge by the Maryland Police Training and Standards Commission or that meets standards established by the Maryland Police Training and Standards Commission under § 3–207 of this article; or (15) intends to use the regulated firearm to: (i) commit a crime; or (ii) cause harm to the purchaser, lessee, transferee, or recipient or another person. (c) A person is not required to complete a certified firearms safety training course under subsection (b)(14) of this section if the person: (1) has already completed a certified firearms safety training course required under subsection (b)(14) of this section; (2) is a law enforcement officer of the State or any local law enforcement agency in the State; (3) is a member, retired member, or honorably discharged member of the armed forces or the National Guard; (4) is a member of an organization that is required by federal law governing its specific business or activity to maintain handguns and applicable ammunition; (5) has been issued a permit to carry a handgun under Subtitle 3 of this title; or (6) is the borrower of a firearm. (d) (1) A person may not sell, rent, or transfer: (i) ammunition solely designed for a regulated firearm to a person who is under the age of 21 years; or (ii) 1. a firearm other than a regulated firearm to a minor; 2. ammunition for a firearm to a minor; 3. pepper mace, which is an aerosol propelled combination of highly disabling irritant based products and is also known as oleo–resin capsicum (O.C.) spray, to a minor; or 4. another deadly weapon to a minor. (2) A person who violates this subsection is guilty of a misdemeanor and on conviction is subject to imprisonment not exceeding 1 year or a fine not exceeding $1,000 or both.