As said, it's a measure of .
Proportionality prohibits the use of any kind or degree of force that exceeds that needed to accomplish the military objective. Proportionality compares the military advantage gained to the harm inflicted while gaining this advantage. Under this balancing test, excessive incidental losses are prohibited. Proportionality seeks to prevent an attack in situations where civilian casualties would clearly outweigh military gains. This principle encourages combat forces to minimize collateral damage—the incidental, unintended destruction that occurs as a result of a lawful attack against a legitimate military target.
Technically it's not illegal to shoot someone with a .50 caliber round if it's the only one that will achieve the desired outcome, as in with a sniper rifle.
So then it is basically illegal to do anything that is impractical. Shooting someone with a .50 caliber at close range wouldn't be practical and there are other rounds better for the job. Whatever is best for its application can be claimed to be the only one that will achieve the desired outcome (proficiently).
Anywhere you can bomb you can also roll up on (at least with insurgents). That's capable of achieving the same outcome. But it has disadvantages, your own potential loss of life. So something does something with less disadvantages to you and that changes some elements of the outcome and therefore isn't illegal.
I'm just saying it's a silly law. Do anything you would do in war anyway, and everything else is illegal.
(post is archived)