This fourth renewed edition of International Law at the crossroads remakes the organization of its chapters and the systematic location of some issues with the aim of simplifying and clarifying the overall vision of this legal discipline. Hand in hand with this General Course on Public International Law the reader will understand the characteristics of the current international society and the status of its subjects; the manner of elaboration, effects and crisis of international standards; how this legal system, setting two complementary obligations, has responded to the conflicts that originate in international relations, namely, that international disputes must be resolved in a peaceful manner and that, therefore, the use of armed force is illegal; the evolution of this branch of law, which has led it to worry in recent decades about the protection of the fundamental interests of the international community, and, finally, the assumptions in which contemporary international law considers that an act is committed illicit and what are the consequences of that violation. This is also an updated edition. Since the previous one, there have been novelties that clearly affect an exhibition of current international law. Such is the case of internal legislative developments, such as the adoption of Law 25/2014 of treaties and other international agreements, Law 14/2014 on maritime navigation, LO 1/2014 on universal criminal jurisdiction or, finally, LO 16/2015 on privileges and immunities. There have also been events or situations in international relations that must necessarily be taken into account in a current International Law Course. Thus, for example, the reiterated claim by the Autonomous Government of Catalonia of the right to decide; the incorporation of Crimea (Ukraine) to the Russian Federation in a context of intervention and use of force in eastern Ukraine; the threat that the self-proclaimed Islamic State represents for the world; the possible use of cyberspace for hostile purposes against other States and the need for its legal regulation; the apparent race towards the control of Arctic resources or, finally, the arrival at the White House of a president that can generate significant developments in today's world. These and other issues of interest are addressed in this book, which seeks to address them with realism but without cornering their critical assessment.