Taking War Seriously: A Model for Constitutional Constraints on the Use of Force in Compliance with International Law

This article develops an argument for increased constitutional control over the decision to use armed force or engage in armed conflict, as a means of reducing the incidence of illegitimate armed conflict. In particular, the Model would involve three elements: a process-based constitutional incorporation of the principles of international law relating to the use of force (the jus ad bellum regime); a constitutional requirement that the legislature approve any use of force rising above a de minimus level; and an explicit provision for limited judicial review of the decision-making process. The Model is not designed with any one country in mind, but address issues raised in recent debates and calls for reform of executive war powers in various liberal democracies.The article begins by looking at the causes of war, which operate at the decision-making level, at the level of state structure, and at the level of the international system. The history of the development of legal constraints on the use of force, however, reveals that while there was an apparent understanding of the need to address the causes of war at both the domestic and international level in the pre-modern period, since the early twentieth century we have almost exclusively relied upon the jus ad bellum regime in international law to constrain armed conflict. Constitutional democracy has spread throughout the world, and international law is increasingly implemented within the domestic legal systems of the world. Yet in most liberal democracies in the world there has been little domestic implementation of the principles of the jus ad bellum regime, the very core of the international law system, or further development of the constitutional principles creating the separation of powers in relation to the decision to use force.The article reviews the theoretical support for the three elements of the Model. Various strands of international law compliance theory, as well as aspects of constitutional theory, provide support for the idea that the incorporation of jus ad bellum principles would further the achievement of both constitutional goals, and enhance compliance with the international law regime. In short, such incorporation would engage the causes of war at the domestic level, and strengthen the compliance with the laws that engage the causes of war at the international level.Similarly, the requirement for legislative approval of decisions to use force would further the realization of the separation of powers envisioned by Madison and Kant. Bringing to bear the representative and oversight functions of the legislature would not only enhance democratic accountability, but would engage the domestic causes of war in significant ways, reducing the factors that lead democracies to wage war with illiberal states, while not undermining the features that help give rise to the democratic peace. Finally, the establishment of explicit jurisdiction and standing for judicial review of the process would help ensure that the other branches comply. The courts would not be second-guessing the substance of executive decision-making, and such judicial review of the process is entirely consistent with theories regarding the role courts play in resolving the agency problems inherent in the democratic system. All three elements of the Model operate in mutually reinforcing ways to engage the causes of war at all three levels, thus reducing the likelihood of illegitimate uses of armed force. The analysis includes some discussion of the likely objections to the Model and its theoretical assumptions.