Written for students working in a range of disciplines, this textbook provides an accessible, balanced, and nuanced introduction to the field of public international law. It offers the basic concepts and legal frameworks of public international law while acknowledging the field's inherent complexities and controversies. Featuring numerous carefully chosen and clearly explained examples, it demonstrates how the law applies in practice, and public international law's pervasive influence on world affairs. Aiming not to over-emphasize any particular domestic jurisprudence or research interest, this textbook offers a global overview of public international law that will be highly valuable to any student new to the study of this very significant field. The 2nd edition has been updated to address the latest developments in the field. It includes new and current examples and cases in key areas, such as human rights law, criminal law, humanitarian law, and environmental law.