United States of America
Practice Relating to Rule 18. Assessment of the Effects of Attacks
The US Air Force Pamphlet (1976) states:
Those who plan or decide upon an attack must refrain from deciding to launch any attack which may be expected to cause incidental 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.
The US Naval Handbook (1995) states:
Naval commanders must take all reasonable precautions … In each instance, the commander must determine whether incidental injuries and collateral damage would be excessive, on the basis of an honest and reasonable estimate of the facts available to him.
The US Naval Handbook (2007) states:
Naval commanders must take all reasonable precautions … In each instance, the commander must determine whether the anticipated incidental injuries and collateral damage would be excessive, on the basis of an honest and reasonable estimate of the facts available to him.
In 1992, in its final report to Congress on the conduct of the Gulf War, the US Department of Defense stated:
Some targets were specifically avoided because the value of destruction of each target was outweighed by the potential risk to nearby civilians or, as in the case of certain archaeological and religious sites, to civilian objects.