BICYCLE LIGHTS LAW REQUIRMENTS IN Delaware
In US the bike lights die required by Law if you reading in low light conditions, The light can be attached to either the bike or to the cyclist but must be visible at least 500 feet to the front of the bicyde, so be careful how you position the light. Additional lighting must be consistent with the law specifying required lights and reflectors, so a rear light must be red.
4198F Lamps and other equipment on bicycles.
(a) Every bicycle when in use at nighttime shall be equipped with a lamp on the front which shall emit a white light visible from a distance of at least 500 feet to the front.
(b) Every bicycle shall be equipped with a red reflector of a type approved by the Department which shall be visible for 600 feet to the rear when directly in front of lawful lower beams of head lamps on a motor vehicle.
(c) Every bicycle when in use at nighttime shall be equipped with reflective material of sufficient size and reflectivity to be visible from both sides for 600 feet when directly in front of lawful lower beams of head lamps on a motor vehicle or, in lieu of such reflective material, with a lighted lamp visible from both sides from a distance of at least 500 feet.
(d) A bicycle or its rider may be equipped with lights or reflectors in addition to those required by subsections (a)-(c) of this section.
(e) Every bicycle shall be equipped with a brake or brakes which will enable its driver to stop the bicycle within 25 feet from a speed of 10 miles per hour on dry, level, clean pavement.