Every civilian killed in conflict is a life wasted. Yet, in the recent fighting between Israel and Hizbullah, both sides have sought to justify the deaths of civilians and the destruction of infrastructure. Amnesty International will not go down this route. We do not condemn or condone war itself, but we do condemn grave violations of human rights and international humanitarian laws wherever they occur and whoever has committed them. That is our purpose and our mission. Inherent human dignity and the right to life are our yardsticks. And where we campaign and advocate to change the behavior of states and armed groups, it is when they have violated international law. What was so disappointing - and indeed astonishing - about Professor Alan Dershowitz's August 31st Post op-ed paper - was his suggestion that both international humanitarian law and international criminal law were a figment of AI's imagination. They are in fact the culmination of a century of effort by nearly all states to develop rules to reduce the scourge of war, especially on civilians. In his critique of AI's report Israel/Lebanon: Deliberate destruction or "collateral damage"? Professor Dershowitz rightly points to the World War II bombing of "the center of towns with the express purpose of killing as many civilians as possible", as a key parallel. But he draws the wrong conclusions. For once the dust had settled, the extent of the catastrophe exacted on civilian populations of Europe and Japan horrified and shamed the international community. It led directly to the further development of the then fledgling international humanitarian law, with the four Geneva Conventions of 1949 and their Additional Protocols of 1977. The laws of armed conflict in 1944 were patchy and inadequate. In 2006, Hizbullah and Israel do not have the same excuse. Beginning with the 1945 Nuremberg statute, and culminating with the statute of the International Criminal Court, the international community developed a body of international criminal law to run in parallel to the Conventions and make sure the most serious violations of these rules would be criminalized. Nearly all states, including Israel and Lebanon, have accepted these laws. Professor Dershowitz apparently has not. A CORNERSTONE of the laws of war is that a distinction be made at all times between civilian persons and objects (infrastructure) and military objectives. According to the evidence gathered by AI, Israel has engaged in indiscriminate and disproportionate attacks aimed at the destruction of the civilian infrastructure of Lebanon. This conclusion is supported, as noted in our report, by direct statements from high-level Israeli officials themselves. Our use of the rule of proportionality, which Professor Dershowitz labels as "idiosyncratic," is the near-universally accepted standard. As described in article 51(5)(b) of Additional Protocol I, a disproportionate attack is that "which may be expected to cause loss of civilian life, injury to civilians, damage to civilian objects, or a combination thereof, which would be excessive in relation to the concrete and direct military advantage anticipated." As the International Committee of the Red Cross says, such attacks can never be proportionate if they cause extensive damage. Dershowitz also objects to AI's point about roads used for military transport still being "primarily civilian in nature." But the law is clear: where there is any doubt, the road is presumed to be civilian. To be a lawful target, military advantage must be concrete and effective, not potential or indeterminate (Protocol I 52 (3)). If Dershowitz's interpretation were correct, Hizbullah's indiscriminate bombardment of Israel would be lawful, since roads in Israel are used both by military and civilians. But Hizbullah's bombing was not lawful. It was criminal. He said nothing about our evidence of bombed supermarkets, water treatment plants and pumping stations; minimizing Israeli attacks on civilian infrastructure in Lebanon as "property damage." But in these and other attacks, more than 1,000 Lebanese were reportedly killed, about one third of whom were children. Disruption to civilian life was immense - including the displacement of a quarter of the population. Dershowitz also has his facts wrong when he implicitly accuses AI of an anti-Israel bias. We have repeatedly appealed to both parties to protect civilians; condemned the bombing of northern Israel by Hizbullah; asked Israel to end disproportionate attacks; called on states providing weapons to either side to stop doing so; made interventions to both the UN Security Council and the UN Human Rights Council; and appealed for a cease-fire once all other ways to stop violations against civilians seemed ineffective. We also publicly denounced the one-sided resolution of the UN Human Rights Council which addressed only violations by Israel. AI delegations have been on the ground in both countries throughout the war, meeting with civilians, government officials and the military. The report that so angered Professor Dershowitz, and our forthcoming one on violations by Hizbullah, are just the tip of the iceberg. But they both set out, starkly and clearly, why an independent and impartial international investigation into violations of international humanitarian law by both sides of this bloody conflict is urgent and necessary. Ensuring accountability is a key tenet of AI's work across the globe. AI is not bound by political opinion, race or religion. Human rights are our compass. We urge you to join us in our defense of them. The writer is senior legal adviser for the International Secretariat of Amnesty International.