Md. Code, Alcoholic Beverages and Cannabis § 6–306

The establishment of the following facts by a seller of alcoholic beverages to an underage individual is prima facie evidence of innocence and a defense to a prosecution for serving alcoholic beverages to an underage individual:

(1) the purchaser falsely represented in writing and supported with other documentary evidence that the purchaser was of legal age to purchase alcoholic beverages;

(2) on the basis of the appearance of the purchaser, an ordinary and prudent individual would believe the purchaser to be of legal age to purchase alcoholic beverages; and

(3) the sale was made in good faith and in reliance on the written representation and appearance of the purchaser.