Of course, the existence of an implicit, let alone explicit, contract between myself and another party would change the picture. The right to demand sacrifices commensurate with the provisions of the contract would then crystallize and create corresponding duties and obligations. No embryo has a right to sustain its life, maintain, or prolong it at its mother's expense. This is true regardless of how insignificant the sacrifice required of her is. Yet, by knowingly and intentionally conceiving the embryo, the mother can be said to have signed a contract with it. The contract causes the right of the embryo to demand such sacrifices from his mother to crystallize. It also creates corresponding duties and obligations of the mother towards her embryo. We often find ourselves in a situation where we do not have a given right against other individuals - but we do possess this very same right against society. Society owes us what no constituent-individual does. Thus, we all have a right to sustain our lives, maintain, prolong, or even improve them at society's expense - no matter how major and significant the resources required. Public hospitals, state pension schemes, and police forces may be needed in order to fulfill society's obligations to prolong, maintain, and improve our lives - but fulfill them it must. Still, each one of us can sign a contract with society - implicitly or explicitly - and abrogate this right. One can volunteer to join the army. Such an act constitutes a contract in which the individual assumes the duty or obligation to give up his or her life. The Right not to be Killed It is commonly agreed that every person has the right not to be killed unjustly. Admittedly, what is just and what is unjust is determined by an ethical calculus or a social contract - both constantly in flux. Still, even if we assume an Archimedean immutable point of moral reference - does A's right not to be killed mean that third parties are to refrain from enforcing the rights of other people against A? What if the only way to right wrongs committed by A against others - was to kill A? The moral obligation to right wrongs is about restoring the rights of the wronged. If the continued existence of A is predicated on the repeated and continuous violation of the rights of others - and these other people object to it - then A must be killed if that is the only way to right the wrong and re-assert the rights of A's victims. The Right to have One's Life Saved There is no such right because there is no moral obligation or duty to save a life. That people believe otherwise demonstrates the muddle between the morally commendable, desirable, and decent ("ought", "should") and the morally obligatory, the result of other people's rights ("must"). In some countries, the obligation to save a life is codified in the law of the land. But legal rights and obligations do not always correspond to moral rights and obligations, or give rise to them.