The Choice of Evils Defense is also called the Doctrine of Necessity    in other states.  This is normally not a proper tactic in a criminal or civil defense case.  This extraordinary defense is a claim that deadly force was used to stop some greater harm that was about to happen. 

Notice that the wording Choice of Evils implies that the actor had a conscious choice and intentionally chose to use deadly force.   The accused that claims this defense must say that the injury was done intentionally to avoid a greater harm that would have happened.  Since no one life is more important than any other life it is an impossible or difficult defense to an intentional killing where there can be no greater harm.  See KRS 503.030 and Choice of Evil defense.

The perfect example of this defense is when one individual is shot and injured to prevent the imminent death of another.   It is not proper to use this alleging that the defendant accidentally or negligently injured someone. 

It is possible to use a defense that a supervening cause took over the blame for the injury.  One example could be that a defective firearm caused an injury.  Notice how this statute is worded that this can not be a defense to an intentional killing and that death was an unexpected result.   

Every situation is different this is for information only and this is not legal advice.