Md. Code, Alcoholic Beverages and Cannabis § 22–2703

A person may possess alcoholic beverages on the premises of a license holder if:

(1) the alcoholic beverages are owned by a member of a club licensed for the sale of beer and wine or beer, wine, and liquor and are consumed on the premises;

(2) the alcoholic beverages:

(i) have been brought on the premises of an on–sale restaurant for consumption and use in a private dining room at a private gathering; and

(ii) have not been provided by the license holder of the restaurant; or

(3) a dance or social event is:

(i) held on the premises of an establishment of a holder of a Class C license; and

(ii) 1. advertised as being bring your own (BYO); or

2. sponsored by a member of the club or by a guest that a club member sponsors.