Md. Code, Alcoholic Beverages and Cannabis § 33–2702

(a) A license holder or an employee of a license holder who is charged with a violation of § 6–304 of this article may be proceeded against on a charging document issued by the District Court for the county or by an indictment returned by the grand jury of the county.

(b) A license holder or an employee of a license holder may not be found guilty of a violation of § 6–304 of this article if the license holder or employee establishes to the satisfaction of the finder of fact that the license holder or employee used due caution to establish that the individual was not under the age of 21 years.