Justus For All

Joshua Brook explains the proportionality principle in The New Republic and also takes some human rights organizations to task for presenting a false picture of what that princple is. The second part is enjoyable, but I think that understanding the first is the most important thing here. From the article:

The proportionality principle requires parties to an armed conflict to balance the expected military advantage of an attack with the expected harm to civilians. The Fourth Geneva Convention prohibits attacks against military objectives where the damage to civilians would be “excessive” in relation to the concrete military advantage anticipated by the attack. Of course, predicting the military advantage and civilian damage that will result from a particular attack is inherently uncertain. Furthermore, the term “excessive” is not defined. Thus, the application of the principle of proportionality–i.e. determining whether a particular attack is disproportionate–is imprecise and involves a large degree of subjectivity. (If missiles are falling on your house or your friend’s house, you are less likely to believe a counterstrike is disproportionate than if missiles are falling on a stranger’s house or your enemy’s house.)

That is about as clear a definition as I have ever seen of this.