A Classical Doctrine

All international law presumes a doctrine of civil war. The subjects and participants of the law of nations have always had to determine whom to welcome among them and whom to refuse. In situations where the lawful order within an individual state is under serious contestation, myriad legal questions emerge between the parties, foreign countries, and the world at large. Is there a point at which an insurgency ceases to be an internal affair and becomes a matter of international law? Who represents the state or nation during a civil war? Should the world recognise one, two, many lawful authorities in a civil war, or none at all? Should the laws, administrative acts, and judgments of insurgent governments and rebel courts be considered valid? Who should be responsible for the harm a civil war causes to foreign nationals or their property? How should the world deal with a manifestly illegitimate or putative government, a government in exile, or a pretender to the throne? Are foreign states permitted – or even obliged – to lend assistance or to intervene? When several warring factions seek the floor in the international institutions of the world, whom should the world listen to, and why?

If international law is understood to have a finite sphere of subjects, then its integrity depends on some implicit or explicit distinction between those who qualify as its participants and those who do not. Accepted legal theory suggests that the recognition of legal subjects is a matter of both fact and law, and that statehood is often evaluated and debated in terms of the criteria of effectiveness and legitimacy.Footnote ¹ A civil war, then, would be an internal conflict in which these criteria are being contested and redefined, possibly leading to a transformation in the sphere of subjects of international law. Who is to distinguish those deemed to be within the sphere from those who are not, and on what basis? Here, the potentialities inherent in the indeterminacies and disagreements of international law give the law both a transformative and a conservative character: the language of the law can be deployed both for and against a revolution, to articulate the differences between the parties, and to persuade the world to adopt a particular framing of the dispute or a particular interpretation of justice.

A brief look at the long history of the questions of recognition and civil war in international law suffices to show that the potential for disagreement is infinite and that law on the matter has never been settled. It is a familiar fact that opposing political sides seldom agree on the legal characterisation of insurgents. But also, more impartial legal observers who might nominally share a similar political perspective, professional attitude, or cosmopolitan ethos have time and again failed to find common answers to the problem. History knows countless labels assigned to those who have been considered legitimate actors or denied a legal standing among nations: privateers and pirates, militias and terrorists, revolutionaries and rebels. More often than not, insurgents have carried multiple such monikers simultaneously, so that one person’s ‘pirate’ has indeed been another person’s ‘freedom fighter’. The legal history of civil wars thus binds together international law with the histories of revolution, empire, decolonisation, and the creation of states in general, raising the fundamental questions that lawyers, statesmen, and judges have for centuries debated about what it means to be a subject of international law, and about who is to be included and who excluded from the family of nations, or even from humanity at large.

This book examines the story of the classical doctrine of civil war in international law, a particular normative vocabulary through which jurists and statesmen debated matters concerning rebellion and revolution from early modern times until the early twentieth century. The expression ‘classical doctrine of civil war’ was coined in 1958 by Jean Siotis, who used it when distinguishing the modern terminology of non-international armed conflicts (which we still know and use) from the language and tradition of the law of civil wars in the preceding centuries.Footnote ² In this usage, the word ‘classical’ refers broadly to the old ‘Westphalian’ law of nations, which facilitated the co-existence of states from the early modern period until the early twentieth century. It was characterised by the legality of war as a final means of dispute settlement, in contrast to the (post-)modern era, in which the use of force is meant to be restricted under an international structure of collective security.Footnote ³ This periodisation is retrospective, of course; the jurists and scholars who wrote within the classical tradition saw themselves as modern and forward-looking authors, even when their work largely involved interpreting and categorising historical precedents. The ‘classical doctrine of civil war’ is therefore a theoretical construct, a useful passage of professional lore, one that offers a sketch of a past against which present-day lawyers may also contemplate the modern law of internal conflicts so as to better understand where it comes from and why it reads the way it does.

The underlying principles of the classical doctrine of civil war – such as the notion of public war, the prohibition of self-help, and the concept of the pirate – originated from Roman law and, as such, were among the oldest in the law of nations. Practically, however, the classical doctrine of civil war was largely a product of the age of sail and steam. It rose and fell with the needs and necessities of European empires, and later the United States, as they dealt with various overseas colonies and when those overseas colonies then began to assert their independence. The problem that the doctrine of civil war commonly sought to address was essentially this: how should states deal with foreign subjects, colonists, and indigenous populations that rose to resist their lawful governments and demanded international recognition? The issue was particularly pertinent in the age of sail, because insurgents would often expand their struggle to the high seas by flying their own flags, commissioning their own privateers, and establishing their own prize courts. Whenever this happened, imperial metropolises and foreign governments found themselves negotiating the difficult question of the legal status of the insurgents – that is, whether and when the insurgents might indeed have standing under the law of nations, as opposed to being dismissed as common pirates and rebels.

Over the centuries, a certain, recurrent pattern of legal milestones emerged in such classical civil wars. An internal conflict would inevitably become a concern in the international domain when an insurgent faction declared its own prize jurisdiction to the world and began to commission warships and privateers to enforce its cause on the high seas. A prize jurisdiction implied valid legal standing before the law of nations; it could thus be claimed that, for the purposes of waging their civil war, the insurgents had authority de jure belli to transfer to the captors ownership of property captured from the enemy.Footnote ⁴ This was typically the first mark of sovereignty that insurgents claimed, and it simultaneously brought before the world their demand to be acknowledged not as pirates but rather as lawful belligerents. In response, governments acting to subdue insurgents in their colonies and overseas possessions typically resorted to the use of belligerent rights at sea, in particular by declaring blockades or by demanding to visit and search foreign vessels for contraband cargo. Under the law of nations, the legality of such belligerent acts was limited to formal states of war only, which in turn raised the question of whether something more than internal policing was at play in such circumstances. Further problems of legal characterisation arose in connection with the treatment of captives (whether held as prisoners of war under the law of nations or awaiting individual criminal trials for treason or piracy), the treatment of foreigners and their property in areas affected by the conflict, questions of public debt, and other aspects of the conflict. Although such issues could be of great legal and practical significance, they nevertheless often remained within the territorial jurisdiction of a state and were thus a degree less intractable than the problem of belligerent rights in the truly international space formed by the high seas.

In response to these legal concerns, domestic and foreign governments, diplomats, scholars, and courts sought to establish a degree of legal certainty by determining the status of the conflict and the parties involved, as well as the legal obligations that would flow therefrom. At the heart of the classical law of civil war was the question of whether or not foreign states could, would, or should declare themselves neutrals, and whether the parties in a civil war could lawfully exercise belligerent rights against their nationals. What was at stake for foreign states was their neutral rights and the protection of their subjects against unlawful depredations, expropriations, and damages. Armed interventions were not out of the question either. Consequently, the question of state responsibility became another common element in classical civil wars, arising from damages caused to foreigners, on the one hand, and from the breaches of neutral duties, on the other. Events arising from a classical civil war were regularly debated before judges in domestic and foreign courts and in its aftermath referred to international arbitration before mixed claims commissions tasked with resolving any remaining international property claims. That said, it should be stressed that even in the contemporary legal imagination the classical law of civil war could have only limited global applicability; its history was dominated by that of transatlantic revolutions. Although nominally presented as universal law, in practice the classical law of civil war was clearly contingent on the imperial priorities of Europeans, and later the United States, in the non-Western world. When dealing with what they called ‘the Orient’, international lawyers maintained the colonial dynamic of difference, which gave little hope to indigenous aspirations of sovereign equality with the so-called civilized nations.Footnote ⁵ In these encounters the classical law could still play a role, but that role was mostly to justify its non-applicability, to the disadvantage of rebelling natives and colonial subjects.

The eventual decline of the classical doctrine of civil war was brought about by the reduction of these insurrectionary encounters on the high seas. This began with the abolition of privateers in the 1856 Declaration of Paris, which made maritime war the monopoly of sovereign states and thus deprived most insurgents of a chance to establish a legitimate presence at sea. Although diplomats and jurists continued to use the legal language of civil war to apprehend and argue internal legal conflicts well into the twentieth century, by the time of the Spanish Civil War their classical concepts and principles had undeniably become obsolete. Despite the efforts of many lawyers to modify and reinvent the classical doctrine to make it better fit the new age characterised by aerial bombings and guerrilla warfare, the conceptual language underlying the classical doctrine was eventually superseded by the modern language of the law of non-international armed conflicts. This replacement took place particularly in the drafting of the Common Article 3 of the 1949 Geneva Conventions, although it took until 1975 for the academic community of legal scholars and publicists working at the Institut de droit international to bury the classical doctrine.

The classical doctrine of civil war is not entirely foreign to present-day legal scholarship. Studies in the law of non-international armed conflicts often note the distinction between the ‘classical’ times of war and peace, on the one hand, and the ‘modern’ post-World War era of collective security, on the other, with introductions to the classical principles serving as a contrast to or precursor of the modern law.Footnote ⁶ Recent scholarship has also produced critical reassessments of the nineteenth-century roots of the modern laws of war,Footnote ⁷ as well as the role of insurgencies in the rise of state responsibility.Footnote ⁸ Civil wars also appear in the general history of international lawFootnote ⁹ and in the field of intellectual history.Footnote ¹⁰ But over the last sixty years there have been few, if any, studies devoted to the classical doctrine of civil war per se.Footnote ¹¹ The present book seeks to make up for this want of attention by offering a narrative on the doctrine’s rise and fall in international law. It places the classical doctrine front and centre and explores the emergence, change, and decline of that body of law in a way that aims to make it understandable and accessible to readers. In doing so, the book takes a new, retrospective look at an old conversation that last took place in the works of Jean Siotis, Erik Castrén, and Roscoe Oglesby some five decades ago.Footnote ¹² Their books are still available in academic libraries, but their relative obscurity, when read from today’s perspective, justifies this revisit of that tradition.

In this book, the classical doctrine of civil war is understood first and foremost as a professional language or a vocabulary of international law.Footnote ¹³ The argument, therefore, is that there used to be a classical language with which international lawyers debated civil wars before the establishment of the vernacular found in international law today. ‘Civil war’ used to be a formal legal concept. The legal principles and concepts of the classical doctrine formed the frame of reference within which statesmen and jurists could express the positions of governments, insurgent factions, or other parties whose perspectives they sought to explain or examine. This is therefore ultimately a story about the rise and fall of a certain way of speaking and writing about internal conflicts in a persuasive way among and across the legal profession. Of course, civil wars as actual historical and political events did not arise or disappear with the classical law concerning them. Insurrection remains a dominant form of warfare in the world today; while the number of inter-state conflicts may have fallen since 1945, the number of intra-state conflicts has at the same time increased.Footnote ¹⁴ International lawyers today study and debate non-international armed conflicts as intensely as ever. But the arguments and principles deployed for this purpose no longer hinge on the legal concept of ‘civil war’ as such, and certainly not in the sense inherited from the days of Pomponius, Grotius, Vattel, Jefferson, Bolívar, Wiesse, Rougier, and Olivart. The difference between the present-day vernacular and the professional language of the classical authors is pronounced, and during the research and writing of this book it has become evident that the classical doctrine has in many ways become inaccessible or even incomprehensible from within today’s legal vocabularies. This book therefore seeks to expand the knowledge available to present-day international lawyers in the hope of making the language of the classical doctrine accessible and understandable once again.

The book has been written at a time of growing geopolitical uncertainty, with the world’s predominant powers beginning to reconsider the illegality of the annexation of territory by force and, by way of consequence, the general renunciation of war as an instrument of national policy in their relations with one another.Footnote ¹⁵ In this light, it should be made clear that this book is not, and never was meant to be, a revivalist history, nor does it seek to glorify the classical law of civil war. It aims to offer a modestly critical post-mortem of the subject, exploring how the doctrine once came to be and then faded away. What will hopefully be proven is that past lawyers do not seem to have escaped the inevitable politics of domination, revolution, and recognition that are the inevitable companion of any legal arguments concerning insurgencies and the making of states in the world at all times. The familiar theoretical message here is that in this field of law there is no escape from the politics of international law, which permeates our understanding of internal conflicts as much today as in the past. No particular set of legal rules, concepts, or principles in history has managed to circumvent the political and ethical burdens that weigh heavily on all legal decision-making concerning war and peace, freedom and union, or the killing of the innocent.Footnote ¹⁶ If the world of international law and the use of force is today exposed to criticism for false universalism, then the classical law of war and peace was exposed to criticism as an apology for naked power between states. There were good reasons for abandoning the classical principles of war and peace in the twentieth century. If today all histories of international law are an implicit expression of politics,Footnote ¹⁷ then perhaps here lies the politics of this book: to avoid any illusions about a past in which things were purportedly better with respect to international law and civil war. One would do well to avoid spurious nostalgia for a past law, whereby it might be possible to somehow ‘bracket’ or ‘civilise’ wars, including even internal ones.Footnote ¹⁸

The classical doctrine of civil war never really worked as a legal ‘system’. Never was there a set of clear, mutually agreed international rules of conduct and responsibility regarding civil wars supposedly agreed upon by states voluntarily and then dutifully adhered to even if they had reason to dispute the potential outcomes. The idea of such a system was implicitly an ideal advocated by nineteenth-century international lawyers writing on civil war, and it forms a thread that runs consistently through the whole narrative – but the successes of this ideal were always very limited. In the age of sail, as in the present day, civil wars represented extreme and exceptional circumstances, in which the shortcomings of international law surface, often because of the lack of an authoritative, objective perspective that could identify the relevant rules and connect them with the pertinent facts in a manner that would leave no room for disagreement. Lacking access to an objective and universal interpretation of the law, jurists and statesmen in the past, as in the present, were often guided more by what they thought was right or just or expedient or advantageous than by the logical application of technical legal rules and principles.

Of Old Men and the Sea

The theoretical problem of civil war was, in a way, a question of jurisdiction and whether the applicable law in an armed conflict should be domestic law or the law of nations. War waged in due form as public war was permissible under the classical law of nations. It was a lawful prerogative of sovereigns, a method of resolving international legal disputes in a binding manner, in contrast to diplomacy, arbitration, and adjudication, whose purpose was precisely to help settle disputes without recourse to that method of last resort.Footnote ¹⁹ War was thus a normal, albeit regrettable, state of affairs. Hugo Grotius stated calmly that war was ‘the condition of those contending by force, viewed simply as such’.Footnote ²⁰ According to Emer de Vattel, war was ‘that state’ in which a nation prosecutes its right by force.Footnote ²¹ Francis Lieber studied the laws of war that were ‘established in a state of violence’Footnote ²² and had himself ‘no morbid feeling about war’.Footnote ²³ Such thinking has sometimes been referred to as a legal procedure, ‘war in due form’, a ‘war-prerogative’, a ‘duel’, or a ‘princely trial by combat’.Footnote ²⁴ The lawfulness and normalcy of war continued to be the paradigm up until the twentieth century, even finding an echo in Oppenheim at the time the League of Nations was beginning to operate.Footnote ²⁵

Few internal conflicts were ‘wars’ in the sense meant by the law of nations. The inviolable authority of states in their internal affairs was a cornerstone of sovereignty. As Jean Bodin put it, ‘the subject is never to be suffered to attempt any thing against his soveraign prince, how naughty & cruel soever he be’.Footnote ²⁶ Authorities of the law of nations agreed. Grotius, for example, concluded that, unlike sovereigns waging public war, any pirates and brigands who did not constitute a state could not avail themselves of the law of nations.Footnote ²⁷ Similarly, Gentili stressed how pirates could not wage war in a proper sense and noted how the Romans had never applied the term ‘civil war’ to their contests with Spartacus or other insurgents.Footnote ²⁸ Throughout the classical law of nations, internal conflicts were regularly accompanied by some measure of legal contestation between the incumbent governments and the insurgents over this question. The rulers and governments, being well in charge of the situations most of the time, sternly maintained their sovereignty and rejected any insinuation that the insurgents were more than rebels and pirates. The insurgents, for their part, did their utmost to challenge the status quo and convince the world that they were more than domestic rebels, more than pirates or brigands, but indeed belligerents: subjects of the law of nations, or at least the laws of war.

In most cases, lawful governments had little difficulty denying domestic rebels any legal standing. Governments were, after all, voices of the sovereign and had the final say on their internal affairs. But there were, broadly speaking, three (or four) categories of legal confrontations where the internal sovereignty of states would come under serious challenge. The first category involved the direct relationship between the incumbent government and an insurgent faction. If an insurgent faction could extend its campaign far and wide enough to force a government to enter into something we might call a state of exception, declaring legal measures that extended the regular limits of a peacetime constitutional legal order, then this would lead to questions about the legal nature of the ongoing conflict. The famous English common lawyer Edward Coke illustrated this very well when he defined a state of war as the moment ‘when by invasion, insurrection, rebellions, or such like, the peaceable course of justice is disturbed and stopped so as the courts of justice be as it were shut up’.Footnote ²⁹ For the most part, governments could still claim to pursue counter-insurrectionary campaigns through domestic law, putting down riots and treasonous uprisings in the name of law enforcement, public order, and criminal justice. But a particular complication was the question of whether captured insurgents were criminals or could be treated as prisoners of war. Widespread insurgencies could produce such numbers of captured individuals that dealing with them as individual criminals – entitled to full procedural and legal rights guaranteed in constitutions or the common laws of the land – exceeded the readiness of governments to accommodate and deal with them by due process.Footnote ³⁰ Conversely, governmental troops could be captured by insurgents, and these captured individuals stood a chance of being returned as part of prisoner swaps or, in a worst case scenario, might be subjected to reprisals for any harsh treatment inflicted on captured rebels. Practices between governments and insurgents might in such cases take forms that resembled the treatment of prisoners of war – a domain under the law of nations. Again, questions would arise as to whether a state of war – a civil war – existed.

A second category of potentially belligerent relations were those where there was international pressure for a government to admit that a state of war existed between itself and a faction of its citizens. These cases involved recourse to de facto belligerent measures against foreign nationals in areas beyond national jurisdiction – that is, on the high seas. Under the general law of nations, the principal effect of a state of war was that its existence brought about binding legal effects and relationships between nations. The rights and duties of belligerents had their counterpart in the rights and duties of neutrals. From the perspective of third states, the problem was how to distinguish between lawful belligerent actions taken by warring parties and unlawful hostilities, unfriendly deeds, and sheer piracy. It was overwhelmingly (though not exclusively) maritime issues that were involved here, because the most tangible international effects of a state of war in the age of sail and steam stemmed from belligerent measures like blockades and visits and searches of ships. Contraband cargoes and even entire neutral vessels might be captured by the belligerents and condemned in their prize courts.

The prize courts of individual nations were at the heart of these events. As already mentioned, prize jurisdiction implied an extraordinary claim of authority, one sovereign’s assumption of power to adjudicate the ownership of property taken at sea from the subjects of another sovereign. Failure to show due regard for the rights of innocent parties, neutrals, or anyone otherwise protected by treaties or international law could lead to diplomatic scandals, confrontations, legal claims, reprisals, and even unwanted wars.Footnote ³¹ Insurgencies and civil wars were fought at sea in this manner, just as international wars were. Whenever a group of insurgents established a prize court and commissioned its privateers, this gave rise to a legal conundrum: what gave these insurgents the right to do so? What distinguished them from ordinary pirates? How could anyone tell the difference? If the conflict was a war, foreign nations were obliged to respect the adjudication of prize tribunals. If it was not war, no such tribunal could be opened, and any insurgent captures were acts of piracy.Footnote ³² Thus, when foreign merchantmen and cargoes began to find themselves in trouble with belligerent actors, internal conflicts and unrest had a habit of turning into matters of international law due to very circumstance. As a consequence, foreign powers would engage in tense discussions with the incumbent governments, and from time to time they would declare themselves neutrals, acknowledging that a war existed between a government and a part of its population.

A third category of potentially belligerent relations arose from violations of foreign property rights within the territorial jurisdiction of the state in conflict. Sometimes these did not differ much from disputes arising from captures at sea, as both could give grounds for property claims, reprisals, and the application of diplomatic protection. Reprisals are known to have been issued in response to maritime captures by ‘pirates’ of a certain nationality as well as expropriations of property rights on land,Footnote ³³ and by the age of revolutions the principle of diplomatic protection was acknowledged by the classics of the law of nations.Footnote ³⁴ When foreign nationals – as residents, investors, creditors, merchants, or otherwise – suffered losses or expropriations due to insurgencies, they would need to seek redress from the state undergoing the civil war or through diplomatic protection from the foreigner’s own government. If at this point the incumbent governments refused to acknowledge the existence of a civil war, they could be deemed responsible for any resultant violations of the law of nations protecting foreign interests. When the practice of privateering was prohibited in the nineteenth century and most civil wars stopped reaching the high seas, state responsibility became an even more prominent question connecting civil wars with the law of nations.

The classical doctrine of civil war was inseparably linked with the problem of recognition, whether it be recognition of states or governments, belligerencies or insurgencies. The two standard theories of recognition – a constitutive theory suggesting that subjects of international law become such through recognition in law, and a declarative theory suggesting that we recognise things because they already exist in fact – were mostly formulated by lawyers in the late nineteenth and early twentieth centuries, though the long history of the law of civil war illustrates how the essence of the problem had been very present in legal arguments for centuries before.Footnote ³⁵ Recognition has been referred to as the most ‘political’ of all questions in the discipline, and for good reason.Footnote ³⁶ Centuries of futile debates suggest that it is impossible to exhaustively determine a priori under what conditions the relevant facts in the world meet the legal requirements of sovereignty, or even what the relevant facts and precise legal requirements (and exceptions thereto) are. The story told in this book corroborates the intractable nature of recognition. While it does not seek to find a solution to the problem, one noteworthy finding emerges from the historical record in this regard: when faced with the question of recognition, courts of law have tended to turn to the official view of their governments in pursuit of an answer. This position – which I shall informally call the ‘Gazette principle’ in reference to William Scott’s decision in The ImmanuelFootnote ³⁷– has offered adjudicators a way to remove the critical question of recognition from their own courts and into the political or constitutional domain. Determining whether an actor is a subject of international law is not a matter for the courts but rather for the state from which the court’s jurisdiction flows, so the argument goes. Modern jurisprudence still largely conforms to this view.Footnote ³⁸ But as will be seen, there have also been exceptions to this principle in practice.

The classical doctrine of civil war became obsolete with the early twentieth century’s renunciation of war. By this time, new theories about collective security and the peaceful settlement of disputes began to take the place of lawful war in international legal thought. This transition led to a crisis (if one may call it such) for the law of neutrality, which still played a key role in the legal vocabulary of civil wars. The transition was not straightforward, and many writers expressed considerable reservations about its feasibility and consequences. But in the end, the concept of civil war and much of the accompanying historical and argumentative language faded away almost imperceptibly, along with many other remnants of classical nineteenth-century law. For many lawyers this posed little problem, as they reinvented the law of civil war as the law of non-international armed conflicts to take its place.

This book tells the story of the law of civil war from the early modern times up to those years. It seeks to explain the way in which the old legal vernacular of civil wars rose and fell in ever-changing state practice, and how the doctrine had a second coming in the literature at the turn of the nineteenth to the twentieth century. The book spotlights a self-evident but often opaque storyline in the history of the law of nations, providing a roadmap (or at least breadcrumbs) for scholars interested in exploring the matter further. For readers’ convenience, a summary of the story can be found in the book’s concluding chapter.Footnote ³⁹