Court ruling on "he needed killing" jury instruction
From Carico v. Commonwealth, an 1870 Kentucky ruling on self-defense:
"Speaking of assured and continual danger to life, this court, in the case in 2 Duvall, defined the principle of self-defense as follows: "Like the sword of Damocles, the threatened danger is continually impending every moment and everywhere. The threatened man may be waylaid or otherwise attacked unawares without the possibility of defense or of escape, and may never, day or night, feel safe, or actually be so, while his enemy lives, who whenever he may see him or wherever he may find him may be anxious and able to kill him. And does either human or divine law require such prolonged agony and peril; or can the best and most prudent men suicidably forbear to strike for riddance, if they have the courage to defend themselves, in the only way of secure and lasting escape?"
Now if a man feels sure that his life is in continual danger, and that to take the life of his menacing enemy is his only safe security, does not the rationale of the principle as thus defined allow him to kill that enemy whenever and wherever he gives him a chance and there is no sign of relenting? But before a jury should acquit they should be well satisfied that the killing was not the offspring of bad passion, but solely of a thorough and well-founded belief that it was necessary for security. And here (p.128)lies the danger of misapplication. It is difficult to be assured that the act was thus necessary and done in good faith. Of that, however, the jury and not the court must judge; and in that judgment they can not be too self-poised and careful before they conclude that the peril of the accused was imminent and incessant, and that he, well assured of it, honestly believed that his only safe remedy was to destroy the power to execute the threats. And if he was authorized to believe and did considerately apprehend that his own exile or the death of his persevering enemy, watching to kill him, was, like the tabula in naufragio, the only safe mode of rescue, might he not lawfully choose his remedy and throw his enemy overboard? Why should he be required still to wait an assault and to endure longer haunting and hazard when he might at any moment become the victim of his own forbearance, and when self-defense might be impossible or unavailing? Why let the sword still hang over him? Why not remove it out of sight when he may, and not passively linger until it unexpectedly falls and strikes his heart unresisted? The recognition of the perfect right to do so in such a crisis appears to us consistent with both principle and policy. It seems to us conservative. It might afford more security and prevent more assassinations than the lame law of punishment ever could, and the manly and opportune assertion of this universal birthright may teach the reckless who thus maliciously beset the pathway of the peaceable that they will be likely to bring destruction on their own heads. This preventive principle will go hand in hand with civilization and philosophical jurisprudence as a palladium of personal security and social order and peace. Properly guarded, it may do more good than harm."