Walzer's supreme emergency doctrine holds that when a state faces an imminent and morally monstrous threat—one that would end civilization or justify tyranny—it may temporarily suspend the normal rules of war, including non-combatant immunity. He used the example of the Allied terror bombing of German cities in 1943–44, arguing that it was a last resort against Nazi tyranny. Critics argue this is a dangerous exception that can legitimize atrocities, while defenders claim it realistically captures the moral agony of existential crisis. Walzer himself later expressed ambivalence about the doctrine, tightening its conditions.

Walzer's work is a landmark in just war theory, but he departs from the scholastic tradition in important ways. He grounds the rules of war in the rights of individuals—specifically the right to life and political community—rather than in divine command or abstract natural law. He draws on the legal concept of *ius gentium* (the law of nations) and on the conventions of international law. He also emphasizes the moral equality of combatants on both sides of a just war, arguing that soldiers on the unjust side still have the right to kill enemy soldiers because they are fighting for their own community. This makes his approach more secular and legalistic than earlier versions.

Walzer's *Spheres of Justice* (1983) argues that different distributive principles should apply to different social goods—money, education, political power, and health care, each belong in distinct spheres. He rejects Rawls's unitary difference principle, which he sees as allowing the rich to dominate the poor across all domains. Instead, he advocates 'complex equality': a society where goods are distributed according to their appropriate spheres, and no good (especially money) can be exchanged for another. This is a communitarian, pluralist theory that emphasizes the social meanings of goods and the importance of democratic deliberation in defining those meanings.

Walzer supports humanitarian intervention to stop genocide or mass atrocity, but he imposes strict conditions: the intervention must be multilateral (preferably UN-sanctioned), genuinely aimed at saving lives rather than advancing national interest, and proportionate to the harm it seeks to prevent. He famously argued for intervention in Kosovo in 1999, but he opposed the 2003 Iraq War as unjustified and imprudent. He emphasizes that intervention must respect the political community's right to self-determination, so it should only be used when the state has failed to protect its own citizens or is itself the perpetrator of atrocities.

Walzer's strength was grounding just war theory in the actual practices of warfare and the moral intuitions of soldiers and statesmen, making it more accessible and practical than abstract theorizing. His insistence on the moral equality of soldiers remains a crucial and contested thesis. Critics argue he is too permissive on 'supreme emergency' and too willing to accept the fog of war. Others argue his framework is too state-centric and fails to adequately address non-state actors, terrorism, and asymmetric warfare. However, his work remains the default reference for military ethics and international law, largely because he captures real moral dilemmas.

Walzer is often categorized as a communitarian because of his emphasis on shared meanings and community values, especially in *Spheres of Justice*. However, he rejects the label, insisting that he is a liberal who recognizes that individuals are embedded in social practices. He argues that justice is not a universal, abstract set of principles but emerges from the particular history and culture of a community. At the same time, he is a committed social democrat and supporter of the welfare state, placing him to the left of many communitarians. He saw himself as a 'critical' thinker who uses the shared values of his community to criticize its failings.

Walzer was an active participant in the civil rights movement in the 1960s and the anti-Vietnam War movement, which profoundly shaped his political commitments. He was the co-editor of the journal *Dissent* for decades, where he addressed issues of social justice, democracy, and foreign policy. His experiences with civil disobedience, opposition to unjust war, and advocacy for racial equality gave his philosophical work a pragmatic, engaged edge. He was not a detached academic but a public intellectual who saw his theories as tools for real-world action, and his commitment to 'democratic citizenship' runs through his entire corpus.