Travis (glad you're "here"!): you asked if we are not told to protect each other. I would say that, no, we are indeed not told that. I don't know of any passage in the New Testament (or Old, for that matter) that might point in that direction. Many people take it for granted that self-defense, or at least defense of another, is instinctive, therefore "natural" and a God-given duty or right. Certainly it is instinctual -- all levels of species have an instinct for self-preservation. However, I don't think Christians are called to live on the level of "nature," and certainly not of brute beasts.
I think you're right that American law has long been divorced from (if it was ever married to) Biblical principles. I'm not sure exactly what distinction you are making between "justice" and "fairness." But, "justice" as defined in the OT (see Isaiah 1 and other prophets, for instance) is rooted in God's character, particularly in his care for the poor, widows, orphans, and generally for the oppressed and disenfranchised. For Israel this frequently meant the "stranger," which meant foreigners. Of course, from our perspective to care for these people would be acts of mercy -- which is exactly the point. In the OT "justice" collapses into "mercy." OUR concept of "justice" is "eye for eye and tooth for tooth," or "getting what one deserves." But what God calls "justice" are those acts by which we care for the weak.
I'm rambling a little (1 AM!) so all of this doesn't directly pertain to your post. Sorry. But, in the case of Sadaam, yes, he probably would try to recruit while in prison. I don't think that justifies killing him.
I think a more important and more basic question is not what the nation should do, but what ethical principles should guide Christians. Nations will always act in their own self-interest as they perceive it. Can Christians use self-interest as an ethical guide? Doesn't seem right to me.
But that's why Christians should, in my opinion, participate in the governing process (even voting) with a certain level of reluctance. I voted -- but then felt like I needed a shower! Neither party has a corner on Godliness (duh), and each includes people who will misuse the power we give them. Each promises to keep us safe. I think that's just one of the lies they have to tell in order to get elected (don't think it's really possible), but their intent is always to do whatever is necessary to accomplish that task (American safety), even if it means killing lots of non-Americans. So, voting for them is giving them power to do that. Doing so is not justice, in the Biblical sense, nor is it loving our enemies. Well, nations will do what nations will do (that's the point of Romans 13, and NOT that Christians are licensed to kill on behalf of the government if so ordered) -- and God will use them for his own purposes as he sees fit. That has nothing to do with Christians. We aren't called to rid the world of evil (as W. claimed our current war on terror would do!), to keep it safe, or to rule the world. We're called to be salt and light and to love all of God's creation as God loves it (Mt. 5:48).