The issue of the use of force in international law is among the most engaging and intellectually stimulating topics within the discipline. At the same time, it is one of the most controversial, raising persistent doubts and debates regarding the effectiveness of international law, and at times even questioning its very existence and credibility.

This subject has come to occupy a central position in contemporary legal thought and political discourse, after having been regarded, a decade or more ago, as a settled and relatively static issue. The study focuses on analyzing state behavior and positions both within and outside the organs of the United Nations. One of the main challenges encountered in this analysis lies in the general and abstract nature of the provisions of the UN Charter governing the use of force in international relations, which has allowed states wide discretion to adopt diverse, complex, and sometimes troubling interpretations.

All states that have resorted to the use of force have been keen to justify their actions and present them as consistent with international law. Another difficulty arises from the vast number and scope of international instruments and documents relevant to the subject. While access to some of these materials has been facilitated by the internet, obtaining others required considerable effort.

It is widely acknowledged that international law remains unable to fully regulate the behavior of many states regarding the use of force. It is equally recognized that a growing gap exists between legal theory and actual state practice in this field. However, does this gap necessarily imply the absence of effectiveness of international law, or does it instead reflect divergent standards of application?

The effectiveness of law does not depend solely on strict compliance with legal rules. Some states strive to appear respectful of international law while, in practice, seeking to justify their conduct and confer legitimacy upon it. In addressing these issues, the book is structured into two chapters. The first examines the unilateral use of force, its prohibition, and the recognized exceptions to that prohibition, including military intervention requested by a territorially competent state. The second chapter addresses the collective use of force, whether within the framework of the United Nations or regional organizations. The book concludes by questioning whether international law can realistically play a prohibitive and regulatory role in controlling state behavior, or whether violations and non-compliance have become an accepted feature of contemporary international relations.