Is intentional killing always wrong?
Yes, it is always unwholesome kamma with the unpleasant future result of disease, injury, or premature death. However, killing is always justifiable (sic). Even the terrorist can justify, at least to himself or herself, why he or she has to murder dozens of innocent civilians. If one were undeluded and totally mindful, there is no way that one could kill any living being. However, human beings are seldom undeluded, and rarely mindful, so they can always justify killing: “If I don’t kill the mosquitos I will get malaria,” or “If I don’t carry out this abortion, the mother may kill herself, or the baby will have a miserable existence as an unwanted child,” or “If we don’t execute this murderer he will kill many more people.” All such justifications make false assumptions based on one’s conditioning, which is nothing but the unskilful mental attitude of aversion, ill-will, or anger. Killing and anger is always justifiable, and only part of being human, but that does not make it right.