Here's another example. In my state, generally you cannot defend your property with deadly force. Stopping the commission of a felony, yes, stopping serious bodily injury to yourself or a third party, yes, but if you see someone stealing some canned goods out of your shed in the backyard, you cannot shoot him from the comfort of your porch -- unless you feel like going to jail. (This kind of theft is probably a misdemeanor, right? So you probably can't use the "stopping a felony" argument.)

In a disaster, however, food may be scarce. You may need your shed of canned goods to survive. The thief reduces your chance of survival and puts you at some risk of death, but it's not like he's shooting at you. So I'm not sure that the disaster would change the situation so much that theft during a disaster counts as serious bodily injury. Does that mean you should let the thief run away with your food? It seems that trying to fight hand-to-hand (which seems more like "reasonable force") would be called for, but it would be an extremely bad idea.

I don't suppose there are too many cases of civilians getting tried for things they had to do to survive disasters. This may be a completely unknown area.