Is a former state-official accused of committing international crimes immune from prosecution before domestic courts? A majority of international lawyers would answer no to that question if posed nowadays. Very likely, however, that majority would have held different views 20 or 30 years ago. How has this change occurred? This paper seeks to tackle this question by, first, looking at the material conditions under which this shift in opinions within the broad interpretive community of international law took place, and second, by exploring the apparent paradox existing in the fact that the whole matter seems to fit awkwardly with traditional accounts of change in international law. The paper will focus on the role that factors such as norm-stability, agency, institutional availability and social legitimacy play in the shaping of international law, as opposed to the traditional requirements of more formal approaches, namely state practice and opinio juris.