D.C. Mun. Regs. tit. 14, § 3908
3908.1 If the hearing examiner determines that the issues raised in a tenant petition affect other tenants or all tenants in the housing accommodation, the hearing examiner may expand the scope of the proceeding to include all affected tenants; provided, that notice shall be given to the additional tenants that they have the right to participate in the proceeding.
3908.2 The notice to other tenants shall state the issues to be decided in the proceeding and that any decision shall be binding upon them.
3908.3 The hearing examiner shall also provide notice to the housing provider of the determination to expand the scope of the proceeding.
3908.4 Tenants and the housing provider shall have a reasonable opportunity to present any arguments in support of or opposition to the hearing examiner's determination.
SOURCE: Notice of Final Rulemaking published at 33 DCR 1336, 1355 (March 7, 1986).