I've linked to some of these already, but there are some thoughtful posts on moral behavior in emergency situations:
* Jimmy Akin has several posts relevant to this subject:
Disaster Ethics 1: Price Gouging
Disaster Ethics 2: Three Moral Situations
Disaster Ethics 3: Taking Things
Disaster Ethics 4: Shooting the Looters?
* Professor Bainbridge:
Shooting Looters: Morally Licit?
* St. Maximos' Hut:
Looting and the absence of the state
* Stop the Bleating!:
* Evangelical Outpost:
"How Can I Help?": Meeting Immediate Needs After Hurricane Katrina
The Battle for New Orleans: Is It Morally Licit to Shoot Looters?
* Acton Blog:
Lootin' in Louisiana
Katrina's Devastations and Emergency Morality
A number of people have discussed how just war theory fits into shooting looters. Strictly speaking, just war theory depends on the ability to extend domestic defense powers against external enemies. If, for instance, the Catholic Church were to pronounce the death penalty intrinsically wrong, all Catholics, to be consistent, would have to become pacifists. Just war is justly applied death penalty to persistent external enemies who are attempting to destroy the community. This, I think, is very clear from Aquinas on. Thus if one accepts just war theory, one has no real ground on which to deny that death penalty might legitimately be given, and in extreme cases, that might require shoot-on-sight orders. That the Catholic Church tends to disapprove of the death penalty as actually applied doesn't give us any insight; the reason it disapproves of punishing citizens by death is that in ordinary circumstances it is not necessary for common good. The real argument for not shooting looters on sight is that we cannot in this way distinguish at all between looters who are looting out of need (starvation, dehydration, or some other such desperate circumstances) and those who are looting out of greed. Need looters are morally justified; greed looters are not. Strictly speaking, need looters aren't looting at all; private property conventions, however important, presuppose common use. In most cases common use requires the observance of private property conventions; however, in emergency cases this is not always so. It can never be justified for us deliberately to act on a policy of punishment that makes no distinction between the guilty and the innocent.
If you've found any other thoughtful posts on this sort of topic, put it in the comments.
[UPDATE: On whether NOLA should be rebuilt or not: The problems with rebuilding it are obvious. There are problems with not rebuilding it, however. NOLA did not become as large as it did by sheer happenstance. New Orleans had what someone once called the worst possible site and the best possible situation. Although it was once much, much better, it's a horrible bit of real estate for building a city, and no doubt. But it seems to me that something is needed more or less where it was (its situation), if we are not planning on completely restructuring the economies of Louisiana and southern Mississippi. It is very clear that a rebuilt NOLA would have to be built so as to have a different sort of relation to Lake Pontchartrain, and particularly so as not to be entirely dependent at any point on a single levee. But it's not at all clear that it could not be rebuilt to be as reasonably safe as most cities are (all cities have to make some compromise between site and situation). If we don't rebuild it, we must ask the next question: Where in the area can we build a city capable of performing the functions New Orleans performed? We won't be able to do without one.]