Maryland State Government Section 10-125
(a)   (1)   A person may file a petition for a declaratory judgment on the validity of any regulation, whether or not the person has asked the unit to consider the validity of the regulation.
(2)   A petition under this section shall be filed with the circuit court for the county where the petitioner resides or has a principal place of business.
(b)   A court may determine the validity of any regulation if it appears to the court that the regulation or its threatened application interferes with or impairs or threatens to interfere with or impair a legal right or privilege of the petitioner.
(c)   The unit that adopted the regulation shall be made a party to the proceeding under this section.
(d)   Subject to § 10-128 of this subtitle, the court shall declare a provision of a regulation invalid if the court finds that:
(1)   the provision violates any provision of the United States or Maryland Constitution;
(2)   the provision exceeds the statutory authority of the unit; or
(3)   the unit failed to comply with statutory requirements for adoption of the provision.