In the Summa, Thomas Aquinas advanced the notion that an action which is well-intentioned may have more than one effect. E.g. trying to preserve one's life may entail a physical defense which results in the death of one's attacker. As long as one's primary intention is self-preservation and not murder, the resulting death of the attacker is, though regrettable, ethically permissible. (S.T. II-II, Question 64, Article 7)
Today we often hear Double-effect invoked in the teaching of ethics to say that as long as the physician's intention in operating on a pregnant mother was to save the life of the mother, the resulting death of her developing child is regrettably tragic, but ethically permissible. Another place where it is invoked is in the case of giving palliative care ("comfort care") to an elderly person who is in a lot of pain, and whose health is fragile. If one administers analgesics to relieve pain, and the patient's constitution is so weakened that they subsequently die, as long as one's objective was pain relief and not euthanasia, this is ethically permissible.
Not a few of my students in ethics feel that this distinction is suspect, and some have voiced that it is just a manipulative usage of terminology to hide one's true intentions. I believe Double-effect is a valid and useful idea. What is your view regarding this issue?