On the question of permissibility, those who believe that Engineer is liable to be killed typically hold that Workman may kill Engineer in self-defense, even if this prevents the saving of the five (Steinhoff 2008: 221). Among those who deny Engineer’s liability, opinion is divided. Proponents of agent-relative prerogatives, such as Quong, hold that Workman is permitted to kill Engineer, at least when this does not prevent the saving of the five (Quong 2016: 827). By contrast, McMahan argues that killing Engineer is impermissible, though Workman may harmlessly prevent the saving of the five in order to save his own life (for example, by remotely jamming the switch that diverts the trolley) (McMahan 2014: 111).