AND THE ISLAMICISTS SIGNED NOTHING:

Morrow begins by arguing that the laws of war are an "international institution." International institutions, according to Morrow, provide the "rules of the game" and make interactions regular and predictable. Morrow then draws on game theory to conceive of countries as strategic actors trying to determine their optimal strategy given a certain set of motivations and incentives. For actors to make strategic decisions on how to behave, they need to have a shared understanding of how the other actors in the game will behave.

During conflicts, the laws of war provide that shared understanding. The preferences that countries express through the negotiation and ratification of these international treaties give insight into what restrictions on war that they are likely accept. In other words, the laws of war both clarify what is expected of countries and provides insight into whether a country is likely to comply. In this way, the laws of war can alter the way that countries choose to behave during conflicts. 

Using this starting point, Morrow generates several hypotheses about when states are likely to comply with the laws of war. Most notable is the hypothesis that overall compliance and the correlation of compliance for a given issue area -- say treatment of POWs -- is likely to be highest when both countries in a conflict have ratified the relevant treaties. The reason for this is that "[w]hen both sides ratify the relevant treaty, they create the shared expectation that one another will comply up to the limits of their control" (p. 87). He also argues that issue areas with decentralized control or higher monitoring costs are likely to have lower average rates of compliance; that first violations are likely to occur early in wars; and that when the first violation comes late in the war the side winning the war is more likely to commit it.

Morrow's dataset consists of all interstate wars from the Boxer Rebellion in 1899 to the Gulf War in 1991.[2] For each conflict, Morrow breaks out pairs of warring states. For example, during World War II, the United States and Japan are one pair of warring states, and the United States and Germany are another. For nine different issue areas governed by the laws of war -- like the treatment of prisoners and protection of civilians -- Morrow codes the level of compliance with the laws of war for each country in the warring pair.

Through both quantitative and qualitative analysis, Morrow finds support for his hypotheses. Most important, Morrow finds that joint ratification of treaties on the laws of war between two countries increases the likelihood that they will restrain themselves during conflict, while also increasing the likelihood that there will reciprocal violations when restraint fails. Based on these findings, Morrow concludes that although the laws of war do not dictate the ways that countries fight, they do shape the ways that countries behave because of the shared expectations that they create.

This argument is most clearly illustrated by Germany's disparate treatment of western and Russian POWs. The western powers and Germany had both ratified the relevant treaties on POWs; and since the western countries indicated there willingness to treat prisoners humanely, Germany reciprocated. Since Russia had not ratified the relevant treaties and did not indicate a willingness to comply with their requirements, Germany did not treat Russian POWs consistently with its legal commitments.

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