D.C. Mun. Regs. tit. 10, r. 10-C3008
In any contested case proceeding by the Mayor's Agent, all parties shall be prohibited from receiving or participating in any ex parte communication with the Mayor's Agent relevant to the merits of the proceeding. This shall include any oral or written communication not in the public hearing record with respect to which reasonable prior notice is not given to all parties to the proceeding.
This prohibition shall begin upon the referral of the application to the Mayor's Agent and shall not terminate until the final disposition of the case.
This prohibition shall not extend to communication between the Mayor's Agent and the staff concerning matters relating to administration of the hearing or matters of record.
D.C. Mun. Regs. tit. 10, r. 10-C3008