D.C. Mun. Regs. tit. 31, § 605
605.1 Each taxicab licensed in the District shall be equipped with a permanently affixed cruising light to distinguish it from other vehicles. No cruising light shall be affixed by magnetic or other means so as to be easily removed.605.2 An association or owner with twenty (20) or more taxicabs may, upon application and approval by the Commission, equip its taxicabs with cruising lights of a design distinctive to that association or ownership.605.3 Applications for approval of a distinctive cruising light shall describe the light in reasonable detail and shall contain a drawing or picture thereof.605.4 No taxicab shall be equipped with a cruising light which has been approved by the Commission for the use of an association or the owner of a fleet of twenty (20) or more taxicabs, unless it belongs to a member of the association or to the owner of the fleet for which the light is approved, or the written authorization of the owner of the fleet to use its cruising light, design and trade name has been obtained and is on file with the Commission.605.5 Effective June 1, 1990, independently operated taxicabs shall be equipped with cruising lights of the design approved by the Commission. Independently operated taxicabs equipped with a cruising light, prior to June 1, 1990, of a design other than the one approved by the Commission for independent taxicabs may continue to operate with that light until the taxicab is replaced.605.6 The cruising light of a taxicab shall be illuminated at all times when the taxicab is for hire during the hours when driving lights are required, and shall be turned off when the taxicab is not for hire.605.7 Whenever a taxicab is responding to a telephone call or previous engagement and is displaying the 'On Call' sign as provided in the Commission's rules, the cruising light shall be turned off.605.8 Whenever a taxicab operator removes his or her vehicle from service and is proceeding to a place of his or her choosing without intending to take on passengers and is displaying the 'Off Duty' sign, as provided in the Commission's rules, the cruising light shall be turned off.605.9 No taxicab shall be operated in the public service unless its cruising light is in proper working condition.605.10 Taxicabs equipped with exterior rooftop advertising pursuant to the Taxicab Commercial Advertising Amendment Act of 1992 shall not be required to be equipped with cruising lights; provided, that the exterior rooftop advertising is illuminated in accordance with the requirements of this section.
SOURCE: Final Rulemaking published at 37 DCR 3595, 3605 (June 1, 1990); as amended by § 3 of the Taxicab Commercial Advertising Amendment Act of 1992, D.C. Law 9-218, 40 DCR 556, 557 (January 22, 1993); and by Final Rulemaking published at 45 DCR 8866, 8867 (December 11, 1998).