This claim is most intuitive when it comes to defending innocent victims from culpable attackers (Fabre 2007). But it is controversial when defending others requires harming innocent persons as the lesser-evil. Recall Trolley, in which Engineer can, at no risk to herself, save five by lethally diverting a trolley towards Workman. Comparatively little attention has been paid to whether Engineer is morally required (and not merely permitted) to save the five. Those who consider the question typically argue that saving is supererogatory, because Engineer cannot be morally compelled to kill Workman (Thomson 1985: 1406; Alexander 2005: 618; Walen &amp; Wasserman 2012: 554).