This problem has generated a number of creative and complex solutions (for a rich discussion, see Tomlin 2020). One strategy holds that liability justifications for killing multiple aggressors can be overridden by the badness of killing (Rodin 2011a: 99; 2017). Related views appeal to the idea that the killing of liable persons leaves a 'residual injustice' (McMahan 2011b: 155–156) or to the notion of combined justifications (see above) to resolve the puzzle (Bazargan 2014). A more radical approach denies that each of the multiple aggressors is in fact liable (Gordon-Solmon 2017) or posits a sui generis proportionality constraint (McMahan 2017).