Chapter 20: The Use of Force
Overview of the Use of Force in International Law
The use of force in international law is recognized as one of the most contentious and complex areas, given the evolving nature of conflicts and legal interpretations. Two millennia ago, Cicero stated, "in war the laws are silent," reflecting the longstanding perception that wartime creates a legal void. This sentiment resonates in contemporary debates about the legality of military interventions, illustrated by a law professor's remarks regarding NATO's intervention in Kosovo aimed at preventing ethnic cleansing. The chapter delves into various conflicts involving the use of force, examining case studies ranging from terrorist actions to classic military invasions such as those of Iraq and Iran, and highlighting how international law struggles to keep pace with emerging threats and realities.
Categories of Military Engagement
Historically, international law delineates two primary categories of engagement related to warfare:
Jus ad bellum: This principle addresses the justification for entering into armed conflict. It evaluates the reasons and conditions under which states may lawfully initiate a war, incorporating factors such as just cause, proper authority, and last resort.
Jus in bello: This governs the conduct and rules of engagement during warfare itself, emphasizing the principles of distinction, proportionality, and necessity to minimize suffering and protect civilians in conflict settings. This chapter emphasizes jus ad bellum, while subsequent chapters will address jus in bello and the implications of modern war crimes trials, which are designed to hold perpetrators accountable for violations of the laws of war.
Defining War
Traditional definitions of war often describe it as an armed conflict between identified states or nations, characterized by a formal declaration or sustained hostilities. However, in an era marked by asymmetric warfare and non-state actors, modern conflicts frequently lack such declarations, leading to the broader use of the term "armed conflict." This encompasses a variety of scenarios, including civil wars, counterinsurgency operations, and humanitarian interventions, challenging the conventional understanding of what constitutes war.
The Historical Context of Warfare and Law
Prior to the 20th century, states operated under a legal framework where resorting to war was not only permissible but often viewed as a legitimate means of conflict resolution. Self-help and self-preservation were the guiding principles of state sovereignty, with armed coercion viewed as a necessary recourse when diplomatic negotiations failed. Textbooks from this era typically delineated laws governing both peace and wartime, but often neglected the complex transitions between these states, reflecting an oversimplified view of international relations.