D.C. Code § 4-210.16

(a) Where a request for hearing has been made on an action taken by the Mayor, and the hearing officer finds that the issue or policy involved directly affects or will affect other recipients or claimants similarly situated, the hearing officer may, upon application by 1 of the recipients who is or will be so affected, allow a class action on behalf of the others similarly situated. The hearing officer, with the consent of the claimants, may consolidate hearings which present similar issues on his or her own motion or at the request of the claimants.
(b) Whenever a claimant challenges a departmental policy or the administrative construction or interpretation of relevant statutes, regulations, orders, or departmental directives, and his or her claim for relief is granted by the hearing officer and the Mayor’s agent because of a misapplication of law contained in the policy, construction or interpretation, the Mayor will correct the challenged policy, construction or interpretation.
(c) Whenever the Mayor changes a policy, construction or interpretation, he or she shall immediately make a reasonable effort to find and notify all recipients affected thereby, and shall make appropriate adjustments in the welfare benefits or decisions of the Mayor which were based upon the erroneous policy or practice.