It is not only enough to ensure that all of your lights are working fine. If you do not turn on the proper lights when you are out on the road at night, you can get fined, or worse, cause an accident. Everyone knows that they should turn their headlights on at night. But driving with only one headlight is illegal. In that case, as a temporary solution, you can use sidelights to let other drivers understand the width of your vehicle. Also, it is a legal requirement to ensure that your brake lights are working all the time. But you can probably get away without a fine for a malfunctioning taillight, albeit being a dangerous thing.