So let me make sure I'm understanding this correctly.....
Each side of your car has two headlights (a small one and a big one).
On one side of the car, the bigger headlight is not functioning.
If this is correct, I would suggest that you get it repaired. If one of the little headlights I would say that you're ok but it could be argued that your vision is compromised and therefore probable cause to make a stop.
Just my take though