Is there a bike light law?

I have lights. I use them. But I don't think it makes me any safer. In fact I would argue the opposite.

I'm going down the road and I can see a car at the junction ahead. With lights I might presume they see me. It can turn out they haven't and you may be going to fast to brake in time. Without lights I will presume they haven't and act accordingly.

What about cars coming from behind? Do you pull over, stop and wait for them to pass before continuing on because you presume they "haven't seen you"? Pigs Arse. You are in this instance fully relying on them to see you, therefore not using lights would have to be the most rediculous thing I've ever heard.