However, if killing Workman is indeed justified as the lesser-evil, this means that Engineer can prevent serious harm to others at no risk to herself, and without imposing a disproportionate cost on anyone else. If we are normally under a duty to aid when these conditions are met, then diverting towards Workman should also be morally required. The challenge is to explain why acting on lesser-evil justifications should be excluded from the more general duty to rescue (Frowe 2018: 465–466).