D.C. Mun. Regs. tit. 18 § 718
At all times specified in § 702, at least two (2) lighted lamps displaying not less than four thousand (4,000) beam candlepower per lamp shall be displayed, one (1) on each side of the front of each motor vehicle, other than a autocycle, motorcycle or motor-driven cycle.
Whenever a motor vehicle equipped with head-lamps as required in this chapter is also equipped with any auxiliary lamp(s), spot lamp, or any other lamp on the front projecting a beam of an intensity greater than three hundred (300) candlepower, no more than a total of four (4) of any such lamps on the front of a vehicle shall be lighted at any one time when upon a street or highway.
Any motor vehicle may be operated under the conditions specified in § 703 when equipped with two (2) lighted lamps upon the front capable of revealing persons and objects seventy-five feet (75 ft.) ahead, instead of lamps required in § 715 or § 716; Provided, that at no time shall it be operated at a speed in excess of twenty miles per hour (20 mph).
Any lighted lamp or illuminating device upon a motor vehicle other than head lamps, spot lamps, auxiliary lamps, flashing turn signals, or emergency vehicle warning lamps, which projects a beam of light of an intensity greater than three hundred (300) candlepower shall be so directed that no part of the high intensity portion of the beam will strike the level of the roadway on which the vehicle stands at a distance of more than seventy-five feet (75 ft.) from the vehicle.
No person shall drive or move any vehicle or equipment upon any highway with any lamp or device thereon displaying a red light visible from the front of the vehicle. This subsection shall not apply to any vehicle on which a red light visible from the front is expressly authorized or required by this chapter.
Flashing lights are prohibited except on authorized emergency vehicles, snow-removal equipment, or on any vehicle as a means for indicating a right or left turn or the presence of a vehicular traffic hazard requiring unusual care in approaching, overtaking, or passing.
The Director shall adopt standards and specifications applicable to head lamps, clearance lamps, identification and other lamps on snow-removal equipment when operated on the highways instead of the lamps otherwise required on motor vehicles by these regulations.
Standards and specifications for lamps on snow removal equipment may permit the use of flashing lights for purposes of identification on snow-removal equipment when in service upon the highways.
The standards and specifications for lamps on snow removal equipment required by § 718.7 shall correlate with and, so far as possible, conform with those approved by the American Association of State Highway Officials.
D.C. Mun. Regs. Tit. 18, § 718