Maryland Code, Public Utilities § 3-201

(a) Notwithstanding § 10-120 of the State Government Article, the validity of a regulation of the Commission shall be challenged in accordance with § 10-125 of the State Government Article.

(b) A party to a Commission proceeding, a person that has been granted intervention in a Commission proceeding, or a person that has been ordered to participate in a Commission proceeding that seeks to challenge a decision by the Commission to act by order rather than regulation shall seek judicial review of the Commission's decision within 30 days after the Commission issues a final order in that proceeding.

(c) Notwithstanding any provision of the Administrative Procedure Act,  1 an order of the Commission issued on or before June 30, 2000 in a generic or quasi-legislative proceeding, that is not the subject of a judicial proceeding pending as of June 1, 2004, is not invalid or unenforceable as a result of the order meeting the definition of a regulation under § 10-101 of the State Government Article.