The Law of Armed Conflict International Humanitarian Law in War

Introduction

At Bunker Hill, in 1775, William Prescott (or was it Israel Putnam?) is said to have ordered his Continental rebels, “Don't shoot until you see the whites of their eyes.” Because the order specified the circumstances in which deadly force could be employed by infantry forces it could be considered an early rule of engagement (except that it is too clear and too brief to qualify).

Rules of engagement (ROE) are not law of armed conflict (LOAC) or international humanitarian law (IHL). They are not mentioned in the Geneva Conventions or additional protocols, and they are not the subject of a multinational treaty bearing on armed conflict. Nor are they are domestic law. They are military directives, heavy with acronyms. ROE are examined here because they play a significant role in executing the state's LOAC/IHL obligations and because they are frequently cited when LOAC/IHL violations are alleged. Most states’ armed forces have some version of ROE to guide their combatants. (The record of U.N. peacekeeping forces and their ROE implementation has been troubled, making a “strong [U.N.] response to provocation close to impossible.”) Although not LOAC/IHL, ROE violations are typically punished through the state's military code. In U.S. practice, violations are prosecuted as violations of a lawful general order, a common Uniform Code of Military Justice offense.

ROE are often misunderstood, even by junior military personnel who are tasked with executing them. Say “rules of engagement” to a naval officer, and she will think, freedom of navigation. Say “ROE” to an air force officer, and he will think, targeting constraints. Say “ROE” to an infantry officer, and he will think, use of deadly force. These viewpoints are variations on a common theme but with different applications, which can make a common understanding of ROE difficult. Say “rules of engagement” to an infantry squad leader, and he will think, “Damn lawyers!”

Each combatant sees this elephant differently, a distinction that can lead to battlefield confusion. The marine colonel Hays Parks goes so far as to write, “Overly restrictive ROEs are a key factor in the loss of confidence by company-grade officers and enlisted soldiers and Marines in their senior leaders and in the exodus of good men and women from the military.”