Stephan, I don't think you can invoke the Catholic Church in your argument for letting the state of Florida kill Terry Shiavo by starvation. The statements you cite from Pope Pius XII are about respirators, not feeding tubes. And just today, we learn in the news that the current pope has been placed on a feeding tube! This, it seems to me, is an indication that the Catholic Church approves of keeping people alive with feeding tubes. Moreover, the Vatican has spoken out against killing Terry Shiavo.
I don't object to quoting clever law professors who wax eloquently about private law -- I do it sometimes myself. I even use Bruce Benson's work in my undergraduate law and economics class. But the fact is, we've had governmental courts in America for more than 200 years, and the original idea for them, and for all government in general, was to protect our natural rights to life, liberty, and the pursuit of happiness. Killing someone by starvation under such dubious circumstances is a direct contradiction of these Jeffersonian/libertarian ideas regarding the proper function of government.
I stand by my earlier comment that the "husband" is a very shady character. He invoked "recovered memory syndrome" seven years after Terri was hospitalized to say that, when they were newlyweds, she supposedly told him to kill her off if she became incapacitated. He got a $700,000 insurance settlement, bought himself two Mercedes and some other goodies, and did not spend one cent on rehabilitation for his wife despite the advice of nurses and doctors that it could help. That's sleazy.