Maryland Code, Land Use § 4-206

(1) may be only of density, bulk, dimensional, or area requirements of the zoning law;

(2) may be only allowed where, owing to conditions peculiar to the property and not because of any action taken by the applicant, a literal enforcement of the zoning law would result in unnecessary hardship or practical difficulty as specified in the zoning law; and

(3) may not be contrary to the public interest.