BICYCLE LIGHTS LAW REQUIRMENTS IN Maine
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.
§2084 Bicycles and scooters
Night equipment. A bicycle, scooter or motorized bicycle or
tricycle, when in use in the nighttime, must have:
1. Lighted a front light that emits a white light visible from a
distance of at least 200 feet to the front;
2. A red or amber light or reflector to the rear that is visible at least 200 feet to the rear; and
3. Reflector material on the pedals, unless the bicyclist is wearing reflective material on the feet or ankles.
A bicyclist may also use optional supplementary reflectors, lights or reflective or lighted safety equipment.