However, what is the "right" to die? Was Terri Schiavo allowed to exercise her rights? Why have anti-suicide laws never been ruled unconstitutional?
It is the implied right, given to us by our Creator, to choose not to exercise our delineated right (given to us by our Creator) of the right to live.
Was Terri Schiavo allowed to exercise her rights?
She was allowed to marry her husband, and by doing so, she transferred much of her parents' role to Mr. Schiavo, her spouse. I don't think that was done involuntarily.
I am not a lawyer, so I cannot comment on the legal aspects of what was done (though I have heard that some decisions were done on an ex post facto basis and that upsets me if true). But from a moral standpoint, "her husband, guardian, and the courts" seem to be the best way society could decide what she would have wanted.
There was an assault on the sanctity of marriage conducted during her life, and that's sad. That doesn't mean I believe a husband has a right to kill his wife, as some might twist my words...but it means that we really have no better way to tell what she would have wanted than the way it was done, in the absence of written documentation.
Why have anti-suicide laws never been ruled unconstitutional?
Are you serious?
What test case would there be? I think that many of those who feel most passionately about this subject are no longer with us. Many find the topic important only after they are in need of relief, and the courts are so slow, many are gone before it does any good. MLK's words are especially relevant, in an odd twist: "A right delayed is a right denied." :-(