Conclusion of this book

The objective of this book was to identify the essential character of the traditional law of neutrality by reconsidering its historical development from the sixteenth century to 1945. To summarise the conclusion of this book, the traditional law of neutrality was an institution that legally protected the right of neutral States not to be involved in war (the “right to remain neutral”), and the so-called “duties of neutral States” were the conditions that neutral States should fulfil if they wished to remain outside the war, rather than the duties of neutral States. The contribution of the conclusion presented by this book as compared to the existing studies is as follows. First, it has been generally assumed and even regarded as self-evident that belligerent States were free at any time to make war on neutral States, and that neutral States did not have the right not to be involved in war in traditional international law. However, the basis of such an assumption is that, in international law prior to the First World War which recognised the unlimited freedom of States to wage war, belligerent States, as a matter of course, should have had the freedom to declare war on neutral States, which had not been proven by the practice of States or legal literature prior to the First World War. The first contribution of this book is that, based on the detailed historical studies, it has proven the existence of the “right to remain neutral”, that is, the right of neutral States not to be involved in war in traditional international law. This book has also identified the basis of this right: The basis of the right of neutral States not to be involved in war was, in State practice from the sixteenth to the eighteenth centuries, agreements between belligerents and third States (neutrality treaties); according to eighteenth-century writers such as Wolff and Vattel, the just war doctrine; and in the period from the nineteenth to the first half of the twentieth centuries, the concept of the causes of war, which limits the personal scope of war. The second contribution of this book is that it has revised the existing explanation about the so-called “duty of impartiality”. It has generally been assumed that neutral States were not permitted to discriminate between belligerents and