Although the possibility of making a choice of law in respect of international commercial contracts has become widely accepted, national law still diverges in many respects with regard to the scope and relevance of, and the limitations on, party autonomy, leading to uncertainty in international commercial relations. This book compares the Hague Principles on Choice of Law in International Commercial Contracts (2015) with national, regional, supranational, and international rules on choice of law around the world in order to chronicle the divergent approaches which exist today. The work is introduced by a comprehensive comparative report which sets out the similarities and differences between the featured national, regional, supranational, and international rules, comparing such rules with those of the Hague Principles, thereby initiating a discussion on further harmonization in the field. Another report focuses on the application of the Hague Principles in the context of international commercial arbitration. Dedicated chapters analyse the Hague Principles from a historical, theoretical, and international organizational point of view. Finally, examining each jurisdiction in detail, the book presents sixty national and regional article-by-article commentaries on the Hague Principles written by experts from all parts of the world. This dedicated and in-depth global comparative study of national, regional, supranational, and international rules provides a definitive reference guide to the key principles in respect of choice of law for international commercial contracts.