The subject matter of this work is exceptionally significant, both for its uniqueness and international relevance, as well as for the implications it holds for law and practice, particularly in recent years. It has inspired various authors (primarily foreign). Still, the resulting works have usually addressed it fragmentarily or incidentally (a natural state of affairs in the development of research trends), rarely positioning themselves within the discipline of legal sciences as a fundamental one. The approach presented in the reviewed work has not yet been adequately represented in monographic form (…). The work is intriguing, evokes scholarly concern (in the positive sense), and encourages academic reflection.Professor Maciej Perkowski The book under review is an essential work in the field of legal science, interdisciplinary in nature (...). The eponymous problem—the development of “cosmopolitan law” and its impact on states, as well as its interactions with traditional legal systems—is fascinating, timely, and worthy of description. It is also worth noting that the author places European Union law alongside traditional legal orders as an “emanation of the state.” The author certainly took on the scholarly challenge of writing the book. And the final result commands respect.Professor Kamil Zeidler