From May 1998 to December 2000, Eritrea and Ethiopia engaged in an armed conflict that cost the lives of thousands of individuals, injured thousands more, and displaced tens of thousands of men, women, and children from their homes. In December 2000, the two sides concluded a comprehensive agreement that ended the war. Among other things, the agreement established the Eritrea-Ethiopia Claims Commission. Consisting of five arbitrators, the Commission’s mandate was to “decide through binding arbitration all claims for loss, damage or injury by one Government against the other” that were “related to the conflict” and that “resulted from violations of international humanitarian law, including the 1949 Geneva Conventions, or other violations of international law.” The two countries filed claims with the Commission in December 2001 and from that time until August 2009, the Commission issued seventeen arbitral awards and eight decisions, covering a broad array of claims, including inhumane treatment of prisoners of war and civilian internees, abuse of enemy aliens in a belligerent’s territory or in occupied territory, wrongful seizure of the enemy’s public or private property, indiscriminate battlefield conduct or aerial bombing, harassment of diplomats and seizure of diplomatic property, and many other matters. The book LITIGATING WAR: ARBITRATION OF CIVIL INJURY BY THE ERITREA-ETHIOPIA CLAIMS COMMISSION seeks to integrate in discrete chapters the Commission’s findings on key topics, with each chapter organized into sub-sections that deal with the principal elements of that topic. The guiding emphasis is not on who-filed-what claim but is instead on what kinds of violations were addressed by the Commission, what kinds of evidence were relevant in establishing or defending against such violations, what legal conclusions emerged in addressing those violations, and what levels of compensation were deemed appropriate when a violation was found.The dominant area of international law upon which claims before the Eritrea-Ethiopia Claims Commission were based was the jus in bello, or the law operating as between two belligerents after an armed conflict has arisen. One type of claim filed before the Commission, however, was quite different, in that it concerned an alleged violation of the jus ad bellum, or the law on when a state may resort to a use of military force against another state. As one of the most important norms for the international legal system, the Commission’s treatment of the jus ad bellum claim is of particular interest, and is addressed in the book’s Chapter IV on “Initiation of War.