Where do rights come from?

I'm pretty sure I have the right to live.

But what if the duly elected representatives of the people passed a law one day saying "all carls must die"?

Would the will of the people have to be respected?

Of course not.

Obviously, the rights of Man do not come from the will of the people, concensus or any such thing.

So, from whence do we obtain our rights as humans?