From National Review:
Why not kill Mrs. Schiavo quickly and efficiently, by depriving her of air to breathe? In principle, that would have been no different from denying her the other basic necessities of life. Why not give her a lethal injection? The law would not have allowed those methods; but the reason nobody advocated them was that they would have been too obviously murder. So the court-ordered killing was carried out slowly, incrementally, over days and weeks, with soft music, stuffed animals, and euphonious slogans about choice and dignity and radiance. By the time it ended, no one really remembered how many days and hours it had gone on. The nation accepted it, national polls supported it, and we all moved on to other things.
Next time it will be easier. It always is. The tolerance of early-term abortion made it possible to tolerate partial-birth abortion, and to give advanced thinkers a hearing when they advocate outright infanticide. Letting the courts decide such life-and-death issues made it possible for us to let them decide others, made it seem somehow wrong for anyone to stand in their way. Now they are helping to snuff out the minimally conscious. Who's next?
I kept asking this exact same question of the pro-death supporters and I never got a straight answer from any one of them either.