Md. Code, Pub. Util. § 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, 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.