D.C. Mun. Regs. tit. 18 § 714
Any motor vehicle may be equipped with not more than two (2) sidecowl or fender lamps which shall emit an amber or white light without glare.
Any motor vehicle may be equipped with not more than one (1) running-board courtesy lamp on each side of the vehicle which shall emit white or amber light without glare.
Any motor vehicle may be equipped with not more than two (2) back-up lamps either separately or in combination with other lamps, but the back-up lamps shall not be lighted when the motor vehicle is in forward motion, nor shall they have a maximum intensity of more than seven hundred fifty (750) beam candlepower per lamp.
Any vehicle may be equipped with lamps which may be used for the purpose of warning the operators of other vehicles of the presence of a vehicular traffic hazard requiring the exercise of unusual care in approaching, overtaking, or passing, and when so equipped may display the warning in addition to any other warning signals required by this chapter.
The lamps used to display a warning to the front shall be mounted at the same level and as widely spaced laterally as practicable, and shall display simultaneously flashing white or amber lights, or any shade of color between white and amber.
The lamps used to display a warning to the rear shall be mounted at the same level and as widely spaced laterally as practicable, and shall show simultaneously flashing amber or red lights, or any shade of color between amber or red.
Warning lights shall be visible at night from distance of not less than fifteen hundred feet (1500 ft.) under normal atmospheric conditions.
When a vehicle is equipped with warning lamps there shall be an illuminated indicator to give the operator a clear and unmistakable indication that the lamps are turned on.
The illuminated indicator shall consist of one (1) or more bright lights flashing at the same frequency as the warning lamps, and shall be plainly visible to drivers of all heights when seated in normal position in the driver's seat while driving in bright sunlight.
Any commercial vehicle eighty inches (80 in.) or more in overall width may be equipped with not more than three (3) identification lamps showing to the front which shall emit an amber light without glare and not more than three (3) identification lamps showing to the rear which shall emit a red light without glare. These lamps shall be placed in a row and shall be mounted horizontally.
D.C. Mun. Regs. Tit. 18, § 714