Who is the most competent to make this decision? The medical professional. Of course government (advised by medical professionals) will set the policy which will constrain the possible decisions.
> Can you imagine scenarios where the state, or the family, or the physician are incompetent, selfish, or malicious in determining the competence of a person? I believe there are MANY such scenarios.
This could apply to absolutely everything: evil police officers taking bribes and releasing criminals, doctors not prescribing expensive medicine to save their hospital money, etc. Does that mean we do away with police protection and hospital services entirely? No, as in this case, we have to accept the risk of the person in authority to make the good decision.
I agree this issue is not black and white.