The fact that some deranged parent wants to kill a five year old is not justification to suspend the civil liberties of the innocent.That makes no sense at all.
Let me repeat the question, in a little more detail. If the parents, as the surrogates for their children, decide to kill them, do you apply the same logic to those particular parents and let them off? The civil liberties of the innocent have nothing to do with it, unless you think killing children is a civil liberty.
Civil liberties have everything to do with it. Protection of the five year old in question is the reasoning the government uses to get themselves involved in family affairs. If your point is to say a five year old is the same as an unborn fetus, I find that arguement rather laughable. Remove a legally abortable fetus from the mother and it can not live, cant feed itself, cant breathe on its own .. therefore it is a total dependant. A five year old can feed itself and doesnt need the mother's blood to live