Gun law in the United States is defined by a number of state and federal statutes.  Sale or delivery of firearms is restricted in Maryland like any other U.S. state.  In almost all the states of the US, an importer, manufacturer, dealer or collector shall be licensed under the federal Gun Control Act of 1968 to be a lawful seller.

A dealer or other person may not sell, rent, or transfer a regulated firearm to a purchaser, lessee, or transferee who the dealer or other person knows or has reasonable cause to believe:

• is under the age of 21 years;
• has been convicted of a disqualifying crime; has been convicted of a conspiracy to commit a felony; has been convicted of a violation classified as a common law crime and received a term of imprisonment of more than 2 years;
• is a fugitive from justice;
• is a habitual drunkard;
• is addicted to a controlled dangerous substance or is a habitual user;
• suffers from a mental;
• 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, or transferee possesses a physician’s certificate that the recipient is capable of possessing a regulated firearm without undue danger to the purchaser, lessee, or transferee or to another;
• is a respondent against whom a current non ex parte civil protective order has been entered under § 4-506 of the Family Law Article;
• 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;
• is visibly under the influence of alcohol or drugs;

Further, a person may not possess, sell, transfer, or otherwise dispose of a stolen regulated firearm if the person knows or has reasonable cause to believe that the regulated firearm has been stolen