By George P. Fletcher and Jens David Ohlin, Oxford University Press, N.Y. 288 pages, $27.95

When the six-month cease fire between Israel and Hamas expired, Hamas, which allegedly had smuggled in longer-range rockets during the truce, resumed rocket attacks on Israeli cities. Israel responded with heavy air and ground attacks. The rocket attacks killed a handful of Israeli civilians and wounded a handful more. Israel’s response killed roughly at least 900 Palestinians, approximately one-quarter to one-third of whom were reported to be noncombatants. Imagine being asked on a bar examination to set forth whether and, if so, why the actions of Israel and/or Hamas were justified under international law.

Although the fact pattern is realistic, the question is not. Bar examiners only ask essay questions to which the correct answer can be found in well-settled law. But, as Professors George P. Fletcher and Jens David Ohlin point out in “Defending Humanity,” issues concerning when a state is justified in resorting to military action are rarely settled in court. There are too few authoritative judicial determinations from which to construct a nuanced body of international law defining the concept of self-defense and how it relates to war. The authors would look to domestic legal systems – both common law and continental – which have well-considered and fully developed doctrines of self defense to help international lawyers fill in the blanks.

International lawyers and legal scholars will be interested in the authors’ theory of self-defense, but “Defending Humanity” is also aimed at political leaders and the general public. “The law of war cannot be restricted to legal scholars who rework the doctrine in the privacy of the academy. International law constrains the behavior of states, and therefore we direct our argument to our political leaders. If Article 51 [of the U.N. Charter] and the law of international self-defense are to be reinterpreted, surely it is they who must hear it.”

The book is efficiently organized and easily absorbed. Chapter one compares law and philosophy, “two disciplines that have shown remarkably little interest in engaging one another” on the issue of self-defense in war. Chapter two surveys the current theories of self defense in domestic criminal law. Chapter three examines self-defense under the U.N. Charter and argues for a more vigorous interpretation that the authors call legitimate defense. Chapter four outlines the elements of legitimate defense; and the remaining chapters apply them to the world’s hot spots: Iraq, Afghanistan, Rwanda, Sudan, Iran, Israel, Palestine, Serbia, Kosovo, etc.

Military action is justified under international law in only two circumstances: a) when authorized by the Security Council to restore collective peace and security, and; b) in case of armed attack, exercise of a state’s “inherent right of self-defense” under Article 51. Since every state justifies its use of military force as self-defense (e.g., the recent Russo-Georgian conflict), reference to domestic legal systems provides a useful basis to help analyze whether the claims of self-defense are legitimate.

When NATO responded with military force when Serbia attacked ethnic Albanians in Kosovo, it was not authorized to do so by the Security Council and no member of the alliance had been attacked. NATO was exercising the right of legitimate defense. The common-law right of self-defense is supplemented by the rights of defense of others and defense of property. The continental right of legitimate defense encompasses all three rights. The French translation of the “inherent right of self-defense” under Article 51 “le droit natural de légitime défense” (the natural right of legitimate defense) is equally authoritative. The authors therefore argue that it is the concept of legitimate defense that provides the true dimensions of the justified use of military force.

Among the most interesting topics discussed in “Defending Humanity” is the comparison between the different way that lawyers and philosophers view war, its ethics and principles of legitimacy. International lawyers appeal to a shared set of authoritative sources: such as the U.N. Charter and the Hague and Geneva conventions. They ask what are the rules and how are they applied. Philosophers reason from first moral principles. Application of the norm is the province of the applied ethicists.

International lawyers differentiate between the concepts of a just war (jus ad bellam) and a justly conducted war (jus in bello). To lawyers, the lawfulness of the war has no bearing on its conduct. Whether attacking or defending, the state may not use poison gas, dumdum bullets or target noncombatants such as civilians or prisoners. To philosophers, anything done to prosecute an unjust war is itself unjust. Philosophers also tend to disregard one of the foundational principles of the law of war. Every combatant is permitted to kill, and is subject to being killed by every enemy combatant, regardless of whether they are in the front lines or back in the rear. The media often conflates the two approaches.

There is also confusion between international law and international criminal law such as when the media cites “proportionality” to compare the number of Israeli civilians killed and wounded by Hamas rockets with the number of Palestinians killed and wounded by the Israeli armed forces. Under international law, proportionality is a “just war” consideration comparing a state’s military objectives with the reason it resorted to force. For example, Israel argues that in order to prevent rocket attacks aimed at its civilians, it is justified in attacking Hamas’ launching sites and combatants – even those in civilian areas – as well as their logistics and resupply tunnels. Under international criminal law, proportionality is a “justly fought war” consideration examining whether the methods used by a state to prosecute its attack have caused too many civilian casualties. Hamas argues that Israel is not entitled to prosecute its attack on Gaza in a manner that has caused the death and maiming of so many noncombatants, particularly women and children.

But what happens when participants in an international conflict are guerrillas? International law governs the conduct of states, as does the law of war. Combatants can kill enemy combatants because they act on behalf of the state. When captured, they have rights as POWS. Hamas de facto governs the Gaza strip. Is it a state? If it is, which of its members are enemy combatants, all, some, or none? Israel and the Palestinian Authority are negotiating a peace treaty. Does Hamas have the right to invoke self-defense to justify its attacks on Israel? If so, should its attacks on civilians subject its leaders to punishment under international criminal law? If it is not a state, should its fighters and their supporters be treated as common criminals or worse? “Defending Humanity” attempts to provide an analytic framework within which the answers to these and other such questions can be formulated. It is well worth reading.

Lawrence A. Mandelker is a member of Kantor, Davidoff, Wolfe, Mandelker, Twomey and Gallanty.