This chapter deals with questions of sovereignty, territory and jurisdiction during the League of Nations era. It discusses how the concept of sovereignty developed until the League era and how it was understood then. Questions of territory and jurisdiction are closely linked with sovereignty, but, given the immense scope of this topic, it will only be considered as far as it affects the central substance of the chapter. This general exposition of the concept of sovereignty will be followed by an explication how the interwar period saw the emergence of, first, its general principle of horizontal protection of the territorial and jurisdictional aspect of states by international law; second, structured exceptions to this principle qua its vertical limitation of sovereignty through the League system; and third, curious cases where the territorial and jurisdictional powers of states had to be reconciled with other innovative legal principles such as human rights and self-determination. These explications will be illustrated and substantiated by a selection of the relevant cases decided by the Permanent Court of International Justice and other judicial bodies.

The League of Nations was the first permanent international organisation with a general mandate. Its establishment is widely regarded as having had a significant, if elusive, impact upon international law, which became centred on international institutions. These three aspects of the League – its permanence, the generality of its mandate, and the ’institutional turn’ it brought to international law – lie at the heart of the assumed significance of the League for contemporary international lawyers. They are regarded as the League’s principal innovations and central components of its legacy, often without much interrogation and rarely subject to sustained analysis. This chapter offers analysis and interrogation to nuance claims about the League’s innovations. It presents the League as an institution whose grand designs often failed, but which innovated quietly and gradually. Above all, it shifts the focus away from the perceived ’breakthrough’ of 1919, and highlights the evolutionary nature of the League, which adapted throughout its life.

The distinction between international and domestic law plays an essential function in the establishment of international law as an autonomous order. During the lifespan of the League, this distinction was contested by scholars and judges in increasingly sophisticated ways. This process culminated in the debate between monists and dualists. However, the formal conceptual foundations of this debate meant that it failed to take account of the way that bureaucrats, officials and experts at the League adopted equally sophisticated normative strategies as part of the ‘experiment of international administration’. Such strategies, which lay at the heart of attempts to promote the ‘well-being and development’ of peoples subject to mandatory rule and foster co-operation across social and economic fields, creatively transformed conventional understandings of the relationship between international law and domestic law. This chapter juxtaposes these simultaneous, countervailing trends of formalisation and deformalisation in international law and administration to offer fresh insight into the crucial formative period in the history of the distinction between international law and municipal law.

The interwar years are the shortest period covered in these volumes, and perhaps the most intense and eventful one. So many things happened in the short course of this quarter of a century that it would deserve an entire Cambridge History series of its own. Unlike other volumes, whose temporal boundaries are harder to establish, this one does not pose a problem. It is firmly locked between the iron parentheses of two devastating catastrophes, if such a pleonasm may be allowed.

The Old Regime period in which war proved the norm and peace the exception witnessed the development of the modern law of nations. Questions of international law assumed a new urgency as did the status of diplomatic agents. By this time the existence of permanent embassies could still be deplored but no longer questioned, and diplomatic immunity could not be disputed, reinforced as it was by a body of precedent and tradition. This period witnessed first the expansion and later the contraction of diplomatic privilege. European aristocratic society reinforced diplomatic privilege, for the status of the ambassador was inextricably intertwined with that of the ruler. The explosive expansion of diplomats and their staff led many theorists, such as Grotius and Vattel, to analyse the evolving conventions, such as the importance of the civil immunity of the ambassador and the liability of the embassy staff. Practice tended to reinforce privileges identified as personal, that is, attached to the ambassador himself. Of these the exemption from criminal liability was perhaps the most important. Among territorially defined privileges, the right of asylum and the notorious right of quarter were first expanded and later either limited or eliminated.

In Renaissance Europe, war and the use of force were regular phenomena and likewise subject of common rules. The theory of ‘just war’, dating back to ancient times, was further developed by legal scholars, and all belligerents claimed to have a just cause, often explained in printed pamphlets. International law consisted of theory and practice, and thus, they should be considered in a mutual context. The focus was still on the question of who had a right to wage war, i.e. on the jus ad bellum, and barely on regulations of warfare or on a containment of war. International law in Renaissance Europe rooted in its very society, in its rules and values. Legal debates and war justifications consolidated the Christian European community, which even in war times did not break apart, even if it was contradictory to the principle of sovereignty and the idea that a sovereign owes no justification to anyone. Moreover, scholars and belligerents argued with natural law and insisted in the universality of international law, although it was in fact basically European. Thus, in Renaissance Europe well-established traditions existed for how to handle war, but they were more and more challenged by the idea of sovereignty, as well as by the European expansion and by global interaction.

This chapter describes territorial conflicts among lords, parishes, cities and towns, and how they contributed to emerging notions of the territoriality of states. It surveys debates regarding both the expansion to new territories and the conservation of existing territories and considers how these debates operated both in Europe and in European overseas colonies. It analyses the writing of jurists as well as a plethora of practices that contemporaries pursued, which despite their obvious local reiterations, were mostly pan-European. Among other things, it covers the question of just war, taking possession of not yet occupied land, discovery, prescription, conservation of the status quo and the role of both conflicts and agreements, including agreements with indigenous peoples, natural law, the law of nations and of relations between territory and jurisdiction. To explain developments during the Renaissance, it observes a much longer time span that began in the Middle Ages and allowed for both slow and revolutionary transformations. It shows that developments in Europe were important, but as vital in both encouraging and empowering change was colonialism, which affected many peoples and territories across the world but also modified Europe in ways we have not yet completely understood.

This chapter is a survey of the legal languages used to govern territory, sovereignty and the right of a ruler within a polity. Debates were heavily dominated by feudal and private law-concepts. Sovereigns maintained the diversity of privileges in the territories ruled in the setting of a composite monarchy. Claims and titles could or could not entail consequences for sovereignty. Reservations and exceptions to full internal sovereignty were not uncommon. Succession quarrels (often causes of war), could be solved by treaty, often in conflict with domestic constitutional rules and principles. Mixed polities (Poland-Lithuania, Holy Roman Empire) offered a broad range of argumentative topoi to either confirm or combat overlordship. Internal German questions could quickly escalate to the field of the law of nations through the game of alliances and guarantees. Although republican forms of monarchy and republican oligarchies were on the decline in the seventeenth and eighteenth centuries, their legal agency was not contested. In extra-European dominions of European sovereigns, the chain of reasoning was significantly lighter, as feudal arguments rarely came into play. Conversely, the agency of subaltern actors in establishing boundaries, or the treatment of native Americans as either allies or subjects provide original avenues of research.