Fortunately, as the world of international commerce matures, the lex mercatoria is developing into a workable system of clearly identified legal principles codified in the UNIDROIT Principles of International Commercial Contracts. In the 25 years since they were first introduced, the UNIDROIT Principles have increasingly found their way from the academic literature into the mainstream practice of arbitral tribunals and of contract drafters in the field of international commerce. In addition to assisting in the interpretation of particular provisions in international contracts, they can also provide guidance more generally on the details of general principles that might apply to the terms of international contracts and on the interpretation of uniform regimes such as the UN Convention on the International Sale of Goods.

Since 1994, the UNIDROIT Principles have undergone three revisions, with each successive edition rendering the articulation of the principles clearer and more representative of the common ground to be found across the divide of common law and civil law and across the divisions that exist within these two legal traditions. As the Principles have increased in detail and specificity, so too have their practical value. So too has the need increased for an authoritative article-by-article commentary explaining the individual articles in context.

It is into this ever more interconnected world that we welcome the definitive reference work on the UNIDROIT Principles by Ekhart Broedermann. The main part of the work containing the commentaries on the 211 articles of the 2016 edition is arranged in 11 thematic chapters following the logic of the life of the contract: 1 – general provisions, 2 – formation and the authority of agents, 3 – validity, grounds for avoidance and illegality, 4 – interpretation; 5 – content, third party rights and conditions, 6 – performance and hardship, 7 – non-performance, right to