How does an international-law doctrine become conventional wisdom without actually having support in the practice of states? It starts with one article asserting the doctrine, but failing to defend it. Then another article makes the same claim, citing only the first article. And then another. And another. And so on — until no one remembers that the first article did not actually identify any state practice at all.
So it is with the “unwilling or unable” test, as indicated by an otherwise quite good new article in the Journal of Conflict & Security Law entitled “Jus ad Bellum and American Targeted Use of Force to Fight Terrorism Around the World.” Consider (p. 228):
With regard to the use of self-defence against private actors located in another state, two consequences flow from the requirement of necessity. First, state practice indicates that the exercise of self-defence against the private actor is conditioned on the inability or unwillingness of the authorities in the host state to stop the private actor’s activities.98 Obviously, if the host state both can and will stop the activities in question, it will not be necessary for the victim state to resort to the use of force.
I’ve left the footnote number in, because it refers to precisely one source: Ashley Deeks’ essay “Unwilling or Unable: Toward an Normative Framework for Extra-Territorial Self-Defense.” An essay in which, as I have pointed out, the author openly admits that she “found no cases in which states clearly assert that they follow the test out of a sense of legal obligation.” (The US and UK have formally endorsed the unwilling or unable test since Deeks’ article was published.)
To be sure, the new article elaborates a bit on the “support” for the unwilling or unable test. But none of that support involves the practice of states — nor does the article acknowledge the inconvenient fact that the Arab League (22 states) has formally rejected the test (post-9/11, even). Instead, it simply says this (p. 229):
The test is widely supported in the literature, and it is also mentioned in two 2013 UN reports by, respectively, the UN Special Rapporteur on extrajudicial, summary or arbitrary executions and the Special Rapporteur on the promotion and protection of human rights and fundamental freedoms while countering terrorism. It also features among a series of “Principles Relevant to the Scope of a State’s Right of Self-Defense Against an Imminent or Actual Armed Attack by Nonstate Actors” proposed by the former legal adviser of the United Kingdom Foreign & Commonwealth Office, Daniel Bethlehem.
“Instant custom”? How passé. Who needs state practice at all? And please don’t bore us by pointing out contrary practice by a bunch of benighted states in the Global South. All we really need are enough scholars, special rapporteurs, and former legal advisors in the Global North willing and able to endorse a particular doctrine and poof — customary international law.