Tony Nicklinson suffered a stroke in 2005. He has zero movement or function, except his eyelids. He is "locked in," not quite a "Johnny Got His Gun" scenario but pretty close.
The story is here.
So, the question: Is it possible for suicide to be a euvoluntary act? What would be the standards for a person to be able to give informed consent that they want a physician to assist them in dying? Should others affected (family members, for example) be required to give their consent also?
To me, the best argument for legality of abortion is the personal autonomy and bodily integrity of the woman. I think abortion is wrong. I also think it is even worse for the state to force a woman carry a growth she considers a parasite to term, when that parasite can be safely removed medically (safe for the woman, though of course NOT for the fetus, which is killed). So, abortion has to be legal, even though it is not euvoluntary (father can oppose abortion, yet it is still done).
If the right of the woman to self determination and autonomy extend even to the "right" to kill the unborn fetus, without the consent (and perhaps over the opposition of) the biological father, how can we possibly justify denying the right of a fully sentient and aware person to make the decision that he wants to end his suffering? All he wants is for his life to be removed medically. How can abortion be legal, when it is clearly not euvoluntary, and yet assisted suicide is illegal, when it is (could be) euvoluntary?