Unilateral action by States in ways that preempt decision otherwise assigned to international organizations is a recurring and sometimes anguishing problem in contemporary international law. Part of the reason for this is to be found in the antinomies of, on the one hand, the monopoly of the use of force assigned to international organizations and, on the other, human rights imperatives. The lecture locates the problem of unilateral action in the different ideal types of constitutive process; some permit unilateral action, others absolutely prohibit it and still others are ambivalent about it.