Double effect: a useful rule that alone cannot justify hastening death.

The rule of double effect is regularly invoked in ethical discussions about palliative sedation, terminal extubation and other clinical acts that may be viewed as hastening death for imminently dying patients. Unfortunately, the literature tends to employ this useful principle in a fashion suggesting that it offers the final word on the moral acceptability of such medical procedures. In fact, the rule cannot be applied appropriately without invoking moral theories that are not explicit in the rule itself. Four tenets of the rule each require their own ethical justification. A variety of moral theories are relevant to making judgements in a pluralistic society. Much of the rich moral conversation germane to the rule has been reflected in arguments about physician-assisted suicide and voluntary active euthanasia, but the rule itself has limited relevance to these debates, and requires its own moral justifications when applied to other practices that might hasten death.