"Humanitarian intervention" as a rare case where bringing jus in bello and jus ad bellum closer makes sense.
I realize suggesting a rapprochement between jus in bello and jus ad bellum may not be the most obvious thing to do at a time when that distinction seems so much under threat (although I do think we are told a little too often that it is under threat). But I would like to push some mildly unorthodox thinking about that relationship, in an effort to think outside the box.
First, I would like to make a general point about the fact that both have a lot more in common than is often acknowledged. For example, the jus ad bellum has a built-in requirement of proportionality which, although quite different from the "tactical" proportionality of the commander in the field, belongs to the same family of idea (restraint in force) and is a sort of "strategic" version of the latter (so that one might think both operate on a sort of continuum). Second, the jus in bello famously has some quasi-jus ad bellum dimension, as when it is decided that wars of national liberation will constitute international armed conflicts governed by Protocol I, or when it imposes looser requirements on guerilla movements than on ordinary armies.
Arguably, these last developments can be described as perversions of the jus in bello, and are often presented as imperiling the distinction with the jus ad bellum. Whatever the case may be, there is at least one more general sense in which the jus in bello and jus ad bellum partake in something fundamentally common even though this is, again, rarely underlined. The jus in bello may be "jus ad bellum neutral" in that it is not partial to a certain type of cause as justifying resort to force, but it does, in a very profound way, tell us what war is (as opposed to which wars are legal). The laws of war do not come to regulate a pre-existing "thing" called war and that exists in nature (the "Solferino fallacy"): rather they constitute that "thing" as a specific form of legitimate violence (the violence is legitimate because of the privilege of belligerency). War is very much, contrary to what appears to be the common (and probably self-serving) humanitarian belief, a social/legal artifact. What makes war war (rather than a brawl, or a feud), according to the jus in bello has traditionally been that it is conducted by the sovereign (or something very much like it), i.e., that it is a public form of violence. If one conforms to that...