While I can't cite a specific case, I think because your question asks about Ethics, you should go back to the Greek emphasis on "public good" and look for a case that pits private against public notions of ethics. For example, what does the law say about parents whose "ethics" do not permit medical treatment for their child's ailment? When the child dies, how is the public good served? You should try to walk the fine line between religious beliefs and ethical stances. Also, who is legally required to define the public good? The Supreme Court? The sitting president? A public survey to determine the prevailing interpretation? Several constitutional elements are currently under investigation for their ethical implications -- stem cell research, gun ownership, capital punishment, cruel and unusual punishment, to name a few. Concentrate on the notion that "the public good" is the criterion, not personal ethics.