Parliamentary war powers and the role of international law in foreign troop deployment decisions: The US-led coalition against “Islamic State” in Iraq and Syria

This article addresses the degree of parliamentary involvement in decisions to deploy armed forces abroad. It observes how the recourse to force by the US-led military coalition fighting against the so-called Islamic State (IS, also known as ISIL, or Da’esh) in Iraq and Syria seems to fit into a broader trend of increased parliamentary control over war-and-peace decisions on both sides of the Atlantic. Inasmuch as international legal arguments can and do play a role in parliamentary debates and concomitant resolutions, this trend carries the potential of contributing to the compliance pull of the jus ad bellum. Against this background, the article explores to what extent newfound war powers on the part of national parliaments go hand in hand with recourse to international legal arguments. The article engages this question through an analysis of the dialogue between the executive and legislative branches in a number of countries (in particular Belgium, the Netherlands, France, Germany, the United Kingdom, and Canada) pertaining to the participation in the US-led coalition against IS.