Being of sound mind, and holding legal capacity to enter into legal contracts, Yes, they do.
If Right is the correlative of duty and wherever one has a right due to him, some other must owe him a duty, then who is it who owes a duty to that person, and what is the duty?
I don't accept the premise that a person's rights obligate a duty upon another person. One's right to take one's own life does not create an obligation for another person to kill him, any more than a person's right to own property obligates an individual to sell him a house.
Rights are action that when taken, do not infringe upon the rights of another. Killing oneself in no way infringes upon others rights.
Of course, two individuals can voluntarily enter a legal contract, obligating a physician to perform certain services (including euthanasia) in exchange for some consideration. There is no difference between this and any other contract, and I don't see any need to explain contract law here.
If persons have an inalienable right to hire a contract killer for such purposes, is the contract assignable?
IMO, only if specified in the original contract and agreed to in advance by both parties.
If the right is inalienable, do minors have the right to enter into such contracts?
No. Minors have unalienable rights, however they are held in proxy by their parent or guardian until the minor becomes of legal age to exercise them. Minors lack capacity to enter into contracts of any kind. A child's parents can exercise the child's rights, but only in their child's best interests. Should a child be terminally ill and needlessly suffering with no real hope of recovery or pain treatment, a parent who has consent from the child could theoretically assert the child's legal right to euthanasia. In such rare cases, great care and supervision should be exercised to ensure that the parent is acting in the best interests of the child.
In your examples there is no duty in with regard to persons in general. Yet for example, a man would have a right to recover property which belongs to him, and which has been unlawfully taken out of his possession. The unlawful possesor would have a duty to return the property. It is generally considered a duty of the state to enforce contracts, which if the law is in one sense an expression of our corporate or collective will, then "we" would have a duty to enforce the contract, with force if necessary.
...Minors have unalienable rights, however they are held in proxy by their parent or guardian until the minor becomes of legal age to exercise them. Minors lack capacity to enter into contracts of any kind. A child's parents can exercise the child's rights, but only in their child's best interests. Should a child be terminally ill and needlessly suffering with no real hope of recovery or pain treatment, a parent who has consent from the child could theoretically assert the child's legal right to euthanasia. In such rare cases, great care and supervision should be exercised to ensure that the parent is acting in the best interests of the child.
We know explicitly from the Declaration of Indepence and the Constitution that children have the right to life. This right is not held in proxy by parents or anyone else. It is absolute and unqualified. The child needs to be of no legal age to excercise this right. It is a right possessed simply by virtue of the fact of the child's being.
In your scenario of a terminally ill child, you are going to have a court deciding what is "in the best interest of the child". Since a court could decide either way, for life or for death, the "right" of the child to be killed is not unqualified. If a court by authority and right can take it away, where the child has committed no crime, then it is not absolute or inalienable.
Think of an instance where the parents by proxy would decide to exercise the "right" of the child to be euthanized, and where the child does not consent. "Mommy, please don't kill me!" Since minors are not considered to have the ability to give informed consent, what would be the "best interest of the child" in such a case? A family court judge could decide the case either way, could he not?
It seems to me that the concept of euthanasia killing as an inalienable right turns traditional concepts of law upside down.
Cordially,