Disagree. A state can't pass ex-post facto laws either. Clearly stated in the Constitution. Ex-post facto means after the fact.
No, the federal courts have said that ex-post facto is a concept only in federal law.
Uh, if "ex post facto" is such a concern to you, then you should be totally against starving Terri, since nutrition was NOT allowed to be denied before Terri was injured. The standard was changed sometime in the 90s I believe.