D.C. Mun. Regs. tit. 31, § 808
808.1 Group Riding for pre-formed groups, as defined in § 899, is permitted at all times. No driver shall refuse to transport a pre-formed group at any time. Fares for Group Riding shall be calculated in accordance with §801.7.
808.2 Shared Riding, as defined in § 899, is only permitted at Union Station, Verizon Center, and Nationals Park at such times as are determined to be necessary to achieve adequate service by a Starter employed or authorized by Union Station, Verizon Center, or Nationals Park. The following requirements shall apply to Shared Riding:
(a) The Starter shall have the sole authority to determine when a taxicab shall depart after taking on passengers, except that after an initial passenger has been taken on, the starter shall not unreasonably delay the departure of the taxicab for the purpose of securing additional passengers;
(b) In the absence of a Starter, shared riding is prohibited.
(c) The general direction of the destination of the first passenger shall determine the general direction of that particular trip. Other passengers whose destinations lie generally in that direction may be transported to the extent of the design capacity of the taxicab;
(d) Passengers shall be discharged in the order of the arrival at their respective destinations. In the event any questions arise as to the order of arrival at any destination, the question shall be resolved in favor of the passenger who entered the taxicab first;
(e) Passengers have the right to refuse Shared Riding; and
(f) Fares for Shared riding shall be calculated in accordance with § 801.7.
SOURCE: Final Rulemaking published at 37 DCR 3595, 3617 (June 1, 1990); as amended by Final Rulemaking published at 44 DCR 7139 (November 21, 1997); as amended by Final Rulemaking published at 46 DCR 5941, 5942 (July 16, 1999); as amended by Final Rulemaking published at 55 DCR 3831 (April 11, 2008); as amended by Final Rulemaking published at 59 DCR 7504 (June 22, 2012); as amended by Final Rulemaking published at 59 DCR 9970, 9974 (August 17, 2012).