Introduction
The Introduction provides an outline of the theme of the book, explaining the focus on state practice, custom, and the codification of international maritime law. State practice and custom were important reference points for the codification of international maritime law, and William E. Hall’s definition of international law serves as a starting point for the reflection on the importance of state practice for the making of international law. History was also an important reference point for early international lawyers, and Theodore D. Woolsey’s explanation helps to understand the close relationship between history and law more generally. The history of international law has become a vibrant research area in recent decades thanks to Martti Koskenniemi, whose works have contributed to the understanding of the construction of a legal argument and the philosophical basis of international law.