Maryland Code, Criminal Procedure § 10-104

(a) Unless the State objects and shows cause why a record should not be expunged, if the State enters a nolle prosequi as to all charges in a criminal case within the jurisdiction of the District Court with which a defendant has not been served, the District Court may order expungement of each court record, police record, or other record that the State or a political subdivision of the State keeps as to the charges.

(b) The District Court may not assess any costs against a defendant for a proceeding under subsection (a) of this section.