D.C. Mun. Regs. tit. 1, r. 1-2913
In DFHV cases filed under §§ 2911.1(b), if the USPS returns to the Clerk's office a default order that was mailed to Respondent for reasons that call into question the accuracy of any affidavit filed under §§ 2911.1(b), (for example, "no such address," "addressee unknown"), an Administrative Law Judge may issue an order requiring the issuing agency to show why the default order should not be vacated. If the issuing agency does not respond with sufficient evidence showing that it mailed the Notice to a valid address for the Respondent, the default order shall be vacated and the Notice of Infraction shall be dismissed.
The default procedure shall be consistent with the applicable law in default cases brought under the DFHV Act and shall ensure that:
A Respondent who fails to answer shall be held in default and shall pay the legally authorized fine and penalty. If the Administrative Law Judge does not find the Respondent in default, the Administrative Law Judge shall dismiss the Notice without prejudice.
D.C. Mun. Regs. tit. 1, r. 1-2913