This book is the first volume of a three-volume treatise on international criminal law (ICL), which is financially supported by the German Research Foundation (Deutsche Forschungsgemeinschaft). The treatise pretends to fill a gap in the academic literature by offering a foundational, systematic, comprehensive, and consistent account of ICL with a special (forward-looking) focus on the International Criminal Court (ICC). The book draws on the author’s academic and practical work on ICL since the 1990s which has not yet been published in a comprehensive form in English. The treatise starts from the theoretical and doctrinal foundations of ICL and takes into account, apart from the case law, the relevant English, French, German, Italian, Portuguese, and Spanish literature to distil general principles of law, essentially derived from the Anglo-American (‘common law’) and Romano-Germanic (‘civil law’) systems, thereby preparing a solid grounding in comparative law for the future ICL. The first volume of the treatise deals with the foundations and general part (general principles) of ICL. In the second volume, the special part, that is the relevant international crimes, their relationship (concursus delictorum), and sentencing will be treated. The third volume will focus on international criminal procedure, cooperation, and implementation. The present volume starts with a short historical overview of ICL (Chapter I) and then deals with the concept, function, and sources of ICL (Chapter II). On this basis, a comprehensive analysis of the actual general part is carried out, that is the imputation and general structure of crime in ICL (Chapter III), individual criminal responsibility (Chapter IV), omission, in particular command responsibility (Chapter V), attempt as a special form of individual responsibility (Chapter VI), the subjective requirements of international crimes (Chapter VII) and, last but not least, grounds excluding responsibility (Chapter VIII). Given the broad comparative approach of the work, each chapter contains a separate bibliography. For reasons of space and to facilitate research, these bibliographies have been published online rather than in this volume. They can be downloaded from http:// ukcatalogue.oup.com/product/9780199657926.do. The chapter bibliographies are complemented by a general bibliography reproduced at the end of the book. In addition, the volume contains nine figures, a list of abbreviations, a table of cases and legislation, and an index.