What situation or event would be so desperate as to expect crime happening?

What events, or occasions where one can expect crime, even if do to the nature of the crime it should be overlooked? When Katrina hit there was a lot of talk about looting, if a person looted for survival goods or for food for themselves or others that was trapped it was OK, but not if you were looting for profit. Crime is crime, and taking something that wasn’t yours is actually stealing. Now after Katrina the ATMs didn’t work, the banks were not open and even if you had money chances are no one was manning the store because they fled, so if you needed nails, batteries, rope, etc you had to loot them from stores that had them.

What if a person’s <insert family member here> needed an operation to save their life but the insurance would only cover 68% of it and the operation would not go forward until the uncovered cost was paid. If they had no credit or not enough to cover it if they went out to jack a dope dealer for his cash would that be acceptable desperation? Would it still be robbery even though the money they were stealing was gotten by illegal means?

What if a group was out sightseeing and the plane goes down in thick growth. After waiting a day with no rescue in sight it is determined they who survived have to move less become prey to wild animals, caught in flash flood water, etc, but one survivor badly injured cannot be moved but barely has a pulse, is bleeding out from a wound that cant be staunched, shallow breath and is becoming jaundice. If one of the survivors creeps over and puts the man down so the others who would not leave him would go and be saved is that a desperate enough of a situation to give a pass on taking a life it by doing so three or more others would be saved?

How would you determine a situation was desperate enough to break the law behind?