Cap Phantom

In addition to the principle of distinction, customary international law bars military attacks that are anticipated to harm civilians excessively in relation to the expected military advantage. This is known as the “principle of proportionality.” The very notion of not inflicting “excessive” harm recognizes that some civilian casualties may be unavoidable when pursuing legitimate military objectives.

By definition, then, evaluation of proportionality (or excessive harm to civilians compared to military advantage) requires balancing two very different sets of values and objectives. States have duties to protect the lives of their civilians and soldiers, but they must balance this against their duty to minimize incidental loss of civilian lives and civilian property during military operations. That is precisely the reason that international law assesses proportionality from the standpoint of a “reasonable military commander,” and the balancing may not be second-guessed in hindsight, based on new information that has come to light.

As with the principle of distinction, a showing of intent is required for there to have been any arguable “war crime” based on excessive civilian harm in comparison with military objectives. In other words, the existence of a war crime turns not on the reasonableness of the commander’s weighing of military advantage against civilian harm, but on whether he or she knew that the attack would cause clearly disproportionate harm, but proceeded intentionally, notwithstanding this knowledge.

The IDF took extensive steps to weigh the risk of civilian harm against the existence of important military objectives, based on the information available at the time of targeting decisions. On numerous occasions, The IDF’s situation analysis frequently led to a decision not to attack legitimate military targets, to avoid the possibility of civilian harm, even though such an attack might not be excessive in relation to the anticipated military advantage.