Except as provided in paragraph (2) of this subsection, a board, commission, or agency head authorized to conduct a contested case hearing shall: conduct the hearing; or delegate the authority to conduct the contested case hearing to: the Office; or with the prior written approval of the Chief Administrative Law Judge, a person not employed by the Office. A hearing held in accordance with § 4-608(f) or § 5-610(f) of the Business Occupations and Professions Article may not be delegated to the Office. With the written approval of the Chief Administrative Law Judge, a class of contested case hearings may be delegated as provided in paragraph (1)(ii)2 of this subsection. This subsection is not intended to restrict the right of an individual, expressly authorized by a statute in effect on October 1, 1993, to conduct a contested case hearing. An agency may delegate to the Office the authority to issue: proposed or final findings of fact; proposed or final conclusions of law; proposed or final findings of fact and conclusions of law; proposed or final orders or orders under Title 20 of this article; or the final administrative decision of an agency in a contested case. Promptly after receipt of a request for a contested case hearing, an agency shall: notify the parties that the authorized agency head, board, or commission shall conduct the hearing; transmit the request to the Office so that the Office shall conduct the hearing in accordance with the agency’s delegation; or request written approval from the Chief Administrative Law Judge to appoint a person not employed by the Office to conduct the hearing. Except as provided in paragraph (2) of this subsection, an agency’s delegation and transmittal of all or part of a contested case to the Office is final. If an agency has adopted regulations specifying the criteria and procedures for the revocation of a delegation of a contested case, delegation of authority to hear all or part of a contested case may be revoked, by the agency head, board, or commission, in accordance with the agency’s regulations, at any time prior to the earlier of: the issuance of a ruling on a substantive issue; or the taking of oral testimony from the first witness. The Office shall: conduct the hearing; and except as provided in paragraph (2) of this subsection or as otherwise required by law, within 90 days after the completion of the hearing, complete the procedure authorized in the agency’s delegation to the Office. The time limit specified in paragraph (1)(ii) of this subsection may be extended with the written approval of the Chief Administrative Law Judge.