 Stephen Nathanson seeks to ground the absolute immunity of civilians or common citizens and the absolute prohibition of terrorism which it entails in a rule-consequentialist ethical theory (Nathanson 2010: 191–208). Adopting civilian immunity, rather than adopting any other rule regulating the matter or having no rule at all, is the best way to reduce the killing and destruction in armed conflict. Moreover, the best consequences will be achieved by adopting it as an absolute rule, rather than as a rule allowing for exceptions in supreme emergencies. The idea of supreme emergency is vague. The criteria for proffering supreme emergency exemptions are liable to be applied in arbitrary and subjective ways. Finally, there is the slippery slope argument: “permitting [departures from the rule of civilian immunity, including terrorism] even under the direst circumstances will lower the bar for justifying such acts … broadcast the message that such behavior may sometimes be justified and … thus lend its weight to increasing the use of such methods” (Nathanson 2010: 207).