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Harvard Law School




This article offers modest reflections on jus in bello proportionality. It suggests that the law of armed conflict (LOAC) build on the only consensus legal standard that exists: that of the good-faith reasonable military commander. The difficulty — here, as with any reasonableness standard — is to identify factors that realistically can, and legally should, guide adherence to it and to consider the objective and subjective dimensions of judgments under the standard. Part II scrutinizes the content and status of Additional Protocol I’s (API) canonical definition of proportionality. It analyzes its text and context to bring out the extent to which API compels more, and more diverse, subjectivities and indeterminacies than commonly recognized. This is not a problem to be solved; it is an inexorable feature of the principle. Part III therefore critiques perhaps the most popular effort to invest proportionality with more precise substantive content: the idea that it requires elites to conduct hostilities "as if" their own noncombatants were the ones at risk. Part IV considers the prospects for promoting proportionality within the spectrum of lawfulness authorized by the current standard. Those prospects depend on dynamics exogenous to the letter of positive international law but not, for that reason, beyond the influence of international lawyers. Empirical data suggest, for example, that the conceptual redefinition of victory in certain conflicts may encourage elites to respect proportionality conservatively as a matter of sound policy. Yet the point lies less in the validity of this example than in what it illustrates: to operationalize proportionality, the LOAC must identify new dynamics that have (sometimes) supplanted reciprocity. Today’s conflicts have their own characteristic dynamics; the comparative demise of reciprocity did not leave a vacuum. These dynamics might well be impressed into the law’s objective of aligning strategic and humanitarian objectives to further the viability and value of proportionality in modern LOAC.


Boston University School of Law, Public Law Research Paper No. 15-21

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