The law applies to people in her condition. It doesn't have anything to do with when she suffered the injury. An analogy would be any tax increase legislation. You can't argue successfully that it doesn't apply to you now because it didn't apply earlier.
Thanks to both of you. I thought the original post was saying a new law forbidding dehydration/starvation couldn't apply to Terri because it would be ipso facto, and therefore unconstitutional. It is (IMO) unethical for Terri to be killed under a law passed after her injury (a law, IIRC, that Felos was actively involved in passing). Also, if Terri did ever mention machines/tubes-feeding tubes were not considered life support or heroic measures at that time. Do you see my problem here?
I see your point, but you have to admit one thing. Since food and water wasn't considered life support at the time Terri allegedly made her remarks, she certainly couldn't have given informed consent to it, which is what is required for living wills. In the absence of a living will, why should informed consent not matter even more strongly?