Can a person forfeit his or her right to life?

[courts]

No one has an inherent "right to life." The state grants it and can take it away, like with all "rights."

Ah ha.  I chose the title intentionally to see if anyone would challenge me on that assertion.  I agree that what we usually think of when discussing "rights" are merely privileges enforced by the state.  But let's discuss rights on a more philosophical or fundamental level.  If there is no concept of a right to life, can one not rationalize murder?  If a person has no right to live, why shouldn't they die?

That's simple, just because someone doesn't believe in a right to life doesn't mean that they can't believe people have an ethical duty to preserve innocent life. Not that I necessarily believe there is no right to life, just saying.