Explain the "Choice of Evils" defense and create a scenario where that defense is likely to be raised.
The general rule is that a person must retreat if they can safely do so before using deadly force. This rule puts a premium on human life-even the life of an attacker. The "castle exception" and the rules regarding the defense of home clearly demonstrate the ancient doctrine that "homes are castles" is still alive and well. In general, a person is not required to retreat from or in their own home before using deadly force.
The facts you give are not really a choice or conflict of law, if the law permits one fact.
A choice of a lesser evil, sometimes known as Competing Harm laws are enacted to excuse/Justify behavior that when engaged in, although a criminal act in itself, was done to commit the lesser harm to society.
Oddly as it sounds sometimes fires are set to STOP a progressing fire, as the absence of trees cuts of the supply of energy, therefore, no fuel, the fire stops. Now Arson is against the law, but if it will stop a spreading fire from reaching a populated area, which is the lesser evil?
Here of course we are speaking of the govt. burning trees, many times exempted from laws in Emergency matters.
I think you get the picture though, just assign another fact pattern and a civilian actor.