If a free person speaks and says -- "No more water, no more food, no more medicine, no more life-support for me -- now!", we might try to cajole a positive response, but without too much delay, we should follow those currently expressed wishes. If the person is a criminal, a prisoner, even a vital witness -- we force him or her to be sustained.
But we pay NO heed to another person's word -- even a spouse or parent -- that a person wants to die. We can't give away what is not ours to give. Nor do we assist a suicide -- suicide differs from refusal of a medicine, or food, or water, because each those individual acts of refusal can be undone later if the mind is changed -- an act that causes a death directly can not be undone. Nor do we pay any heed to a prior contract -- a "living will", whatever to assume that what a person said when in the full sense of health that he would not want to live uner "those" conditions. For no one knows what will be in their mind when that condition (G-d forbid) happens. Ask those who have been through it! People who have come through PVS, through coma, through permanent severe impairments come in many many cases to deny their pre-wishes made when healthy and hardy, and instead come to choose to continue to want to live. Just look at Stephen Hawkings, or Chris Reed -- the will to live is primal.
I disagree. Any extension on life beyond what was allowed in biblical times is due to man's progress. At some point, we can refuse that artifical extension of life that was not available throughout history and die in peace - not artifically surviving due to medical advances.