You cannot make sense of the American legal system. It is complete sophistry. Words do not mean what we laymen think they mean. Rulings are inconsistent and depend predominantly on the disposition, philosophy, or ideology of the presiding judge.
Because of this, it is almost impossible to really "know" where you stand on any given legal issue.
The Sciavo affair seems to me (but, hey, what does a mere layman know?) to be a very straitforward issue of violation of contract -- specifically, the marriage contract. Michael had an adulterous affair, which would be grounds in any court in the country for a divorce. But Terri was physically incapable of launching such a civil suit.
Nevertheless, this evil, evil man was permitted to exercise jurisdiction over his wife as part of that very same marriage contract, and effectively order her execution! Now substantial evidence that suggests he physically abused her prior to the onset of her terminal disability.
So all you have to do in order to violate a contract with impunity is disable the other contracting party to the point where he or she is incapable of starting a civil suit.
But this is just one example of how the law has become essentially meaningless. People are arguing this issue from the perspectives of right to life vs. right to die. That's not the issue at all.
It's about contracts, and it demonstrates that agreements are unenforceable unless you have sufficient financial resources to shepherd a case through the entire appeals process. Basically, it's rich man's justice. The only exception to this is when you become an "enemy of the state", such as Martha Stewart.
In this, at least, socialist critics of the American "legal" system are right. If there is ever justice for "the little guy" this usually occurs only because it is in the interests of the state to do so.
I can't believe I'm saying this to you, because you should know better. Marriage is not a contract, it's a sacrament . This is important because viewed as a contract it becomes an agreement between people who exchange services as opposed to a covenant before God where they promise themselves to each other.
If laws against adultery, which protect both parties but particularly the women, were enforced we wouldn't be having the discussion and Michael Schivao would be in jail where he belongs.