In a previous post, I mentioned that beside the natural duty not to murder, there is a natural duty to rescue people.
Rescuing is the opposite of putting people on permanent welfare; that is, once saved, a person should go out and live his own life, earn his own keep, and wise up by trying not to get in more situations from which he needs to be rescued.
Why, then, is murder illegal, yet failing to rescue is not?
A pragmatic reason is that it’s extremely difficult to prove a violation of the duty to rescue in a court of law. There are so many conditions that differ in every case that need to be present in order for the violation clearly to occur.
Only the potential rescuer can really make the judgment call at the time and place of the decision as to his obligations. It is unfitting to second-guess him.
Failing to rescue is a kind of inaction, dangerously close to minding one’s own business; the accused can argue that the duty fell to another person; he can argue that he’d have endangered himself unacceptably if he had tried to rescue; etc.
Detection of non-rescuers is much more problematic that discovering murderers.
Rescuing is an imperfect duty in the Kantian sense; it is not always in force but arises usually only upon a confluence of some very specific circumstances. Probably most duties to rescue come up and are discharged within families. Other duties are explicitly contractually acquired, such as when the Coast Guard responds to a distress call from a ship. Still other duties to rescue get their poignancy from the extreme conditions surrounding moral agents, such as an Alaskan snowstorm. The duty not to murder, on the contrary, is a perfect duty. One can never take a break from not murdering.
Murder entails the perpetrator’s hatred of the victim, intent to harm, but failing to rescue entails at the most a variant of “depraved indifference” which may be immoral but non-legally-culpable.
In other words, perhaps rescuing is a supererogatory work of mercy, an act of charity; not killing is a required work of justice.
Finally, at its most basic, a murderer initiates violence; a non-rescuer does not.
Therefore, it does not belong to the state to prosecute these particular alleged derelictions of duty.