The changing law of non-intervention in civil wars – assessing the production of legality in state practice after 2011

ABSTRACT It is, especially since the beginning of the ‘Arab Spring’, increasingly difficult satisfactorily to draw the line between an unfriendly but legal interference and an unlawful intervention. This article identifies as one root cause for the material vagueness of non-intervention the fact that on the formal level, the underlying parameters determining the formation and change of customary law are equally imprecise. Current state practice shows that, rather than solely distinguishing between legal and extralegal reasoning, states use a spectrum of reasoning adjusted to the political, moral or strategic relevance of the issue in question. This article suggests how to deal with governmental behaviour that cannot be classified within the existing categories without provoking even more controversies. Emphasis should be placed on the sub-tunes of state behaviour as it is, in fact, this in-between stage that states use to test, reformulate or ultimately reject what is potentially a new legal argument.