The harmonisation of private commercial law and the application of the various instruments of harmonisation are becoming increasingly complex. New formal or informal means of harmonisation are added to the panorama of harmonisation instruments and new actors, be it at global, regional or national level, are introduced as well. Regional harmonisation sets its footprint both internally and externally. Innovative (or reintroduced) methods and phenomena for the harmonisation of commercial law have been suggested. Still, the most important and dominant means of harmonisation are the traditional multilateral conventions, the flexibility of which have been improved by different types of reservations and review and/or revision clauses. Taken together, the harmonisation process with its various and different means constitutes a circle of law harmonisation, in which circle there is an interaction between, and reciprocal influence of, all the various formal or informal means of harmonisation. This book analyses the process of law harmonisation with the focus on choices, limits and consequences. It takes into account means, methods, role of old and new actors, principles of interpretation and gap-filling, impact of judicial bodies and their lawfinding and possible law-making function. An important issue, which transcends the work, is how to strike the balance between the harmonisation by formal means of legislation and the creative law-making role of jurisprudence and doctrine in order to accommodate the promotion of a dynamic and continued progress in the harmonisation, the necessary degree of predictability and legal certainty, and a clear distinction from the otherwise non-harmonised applicable national law.