Andrew McCarthy has a brilliant article on the Terri Schiavo situation in Florida. His basic thesis can be summed up fairly easily. Terri Schiavo is under the care of other people. By removing the feeding tube, those people are causing her to die. There is no difference between removing the tube and shooting her in the head.
McCarthy distinguishes this case from a brain dead patient:
"If a person is brain dead — meaning, in layman's terms (which are the only terms on which I understand the concept), for all intents and purposes dead but still respirating by artificial means — there would seem to be little doubt that a judge is empowered to discontinue the artificial means. In such an instance, the judge (and whoever pulls the plug) is not intentionally causing death or pain. Instead, death has already occurred, and it is merely the artificially supported functions that are being terminated. But, as noted above, that is not the Terri Schiavo case. She is alive; someone has to do something affirmative and intentional to snuff out that life and cause her death. That affirmative act began Friday afternoon."
So, the distinction is that in the brain dead patient’s case, the patient is already dead, while in Terri's situation something needs to be done for her to die.
A reasonable argument against this comparison is that in both cases we are merely preventing her from receiving medical care. (here and here). At the beginning of the article, he implicitly responds to this argument:
"Terri is not a person who is brain dead or a corpse being sustained by artificial means. She is alive and merely needs nutrition, like any child or incapacitated adult needs food and water. She will not be dead unless someone actually takes action to kill her. "
In other words, denying her nutrition is an affirmative act, and not just allowing a person to die (which is passive).
Let's assume that Terri wanted to die in this case. Hilzoy argues that:
"First, in this country competent adults have the right to decline medical treatment. This is a very good thing, since many of the things doctors do to their patients would constitute assault if done against those patients' wills. It is this right that allows cancer patients to decide not to undergo that last excruciating round of chemo that would give them only a slight chance of survival, Jehovah's Witnesses to refuse the blood transfusions that they believe it would be sinful to receive, and people with painful terminal illnesses to refuse treatment for other diseases, like pneumonia, that offer them the chance of an easier death. This right is extremely important: without it, we could be subjected to serious assaults on our body without our consent, so long as some physician said that those assaults were medically necessary."
The issue is not about killing her, but as Rivka notes, whether "it is legitimate to refuse medical treatment intended to prolong her life." It's about recognizing bodily integrity. So Terri wanted to die, and we should obey those wishes. And had Terri asked to be shot in the head or chopped up with an ax, we wouldn't because that would be taking matters into our own hands (i.e., by committing an affirmative act).
On to my two cents:
I do not understand how medical care and nutrition are analogous. Medical care comes up when something unusual occurs; without care, the person will die. If we accept the concept of autonomy, we must obey her wishes. But nutrition is an entirely different idea.
Let's compare food and hydration to air. Let's say a person needed a tube to supply air. Would we respect her wishes if she asked to have the tube removed? I would have to guess Hilzoy would say yes. But can we place a bag over her head? Why not? We aren't actually killing her. We are just preventing her from receiving air. And if we believe in autonomy and know she would want to receive no more air, what's the difference?
Maybe the difference is there's a tube sticking into her body and keeping it there violates her right to autonomy while placing a bag over her head has nothing to do with autonomy. But let's say we developed some Star Trek gizmo that allows us to beam the oxygen directly into her lungs. Would that be ok even if she didn't want it? Is the right of bodily autonomy merely about preventing people from sticking things into our body? I doubt it. The idea seems to be rooted in allowing us to make crucial decisions about our life. If we choose to have no more food or drink or even air, even if those necessities could be administered without a single cut, should our wishes be denied?
The truth is, under Hilzoy's analysis, we should be able to place a bag over Terri's head. Yes, she can breath alone, but she wanted to die, and as long as we take no affirmative action to kill her (which is an act that stops the body from keeping up its vital processes), I see no reason to distinguish between removing the tube and placing a bag over her head.