The morality of participation in an unjust war -- The doctrine of the moral equality of combatants -- The traditional criterion of liability to attack in war -- Can unjust combatants satisfy the principles of Jus in Bello? -- The basis of moral liability to attack in war -- Arguments for the moral equality of combatants -- Justification and liability -- Consent -- The boxing match model of war -- The gladiatorial combat model of war -- Hypothetical consent -- The epistemic argument -- Institutions as sources of justification -- The duty to defer to the epistemic authority of the government -- The duty to sustain the efficient functioning of just institutions -- Fairness to fellow participants -- The collectivist approach to the morality of war -- Transferred responsibility -- Symmetrical disobedience -- Conscientious refusal -- Excuses -- Sources of allegiance to the moral equality of combatants -- The conflation of morality and law -- The conflation of permission and excuse -- Excusing conditions for unjust combatants -- Duress -- Epistemic limitation -- Diminished responsibility -- Skepticism about excusing unjust combatants -- Consistency -- Are unjust combatants excused by epistemic limitations? -- Liability and the limits of self-defense -- Different types of threat -- The relevance of excuses to killing in self-defense -- Culpable threats -- Partially excused threats -- Excused threats and innocent threats -- Nonresponsible threats -- Justified threats and just threats -- Liability to defensive attack -- The moral status of unjust combatants -- Liability and punishment -- The relevance of excuses to the distribution of risk -- Child soldiers -- Civilian immunity and civilian liability -- The moral and legal foundations of civilian immunity -- The possible bases of civilian liability -- Civilian liability to lesser and collateral harms -- Can civilians be liable to intentional military attack? -- Civilian liability and terrorism.