Peace treaties as sources of international law

Rafał Rybicki, PhD,
Wrocław Law School
(Wrocław, Poland)

Bartosz Ziemblicki, PhD,
Wrocław University of Economics
(Wrocław, Poland)

This article discusses the position of peace treaties within the system of international law. The article includes analysis of terms “peace treaty” and “peace agreement” in the context of international agreements treated as one of the major sources of international law (currently an international agreement is the most commonly used instrument for creating norms of international law). The authors believe that the topic itself, as well as the approach proposed by them deserve broader discussion.
A peace agreement (peace treaty) is an international agreement concluded by the fighting parties, which aims for the final and lasting conclusion of the armed conflict, the establishment of peace and the restoration of normal relations between the parties. Peace treaties might be concluded by states, as well as by other entities of international law.
Question of the modern peace treaties and their role in the system of international law should be treated with great attention as there are several armed conflicts ongoing around the world. In many cases, peace talks are conducted in parallel to the actual fights, with strong support of international community. Knowledge about the position of peace treaties as sources of international law is important in the process of implementation and execution of contemporary and possible future peace treaties.
The article discusses several types of most common contemporary peace agreements, including both those qualified as ‘proper’ international agreements as well as other agreements that could not be treated as sources of international law (e.g. intra-state agreements between political parties). The authors conclude that that the factor that makes it possible to qualify particular international agreement as a peace treaty is the aim of final and lasting conclusion of the armed conflict, establishment of peace and the restoration of normal relations between the parties.
Keywords: international law, public international law, international agreement, peace, peace treaty, peace agreement, peacemaking, sources of law, sources of international law, law of treaties.

1. Introduction
International law is a very specific legal system. A system that does not have elements characteristic for other legal orders – catalogue of sources of law, clear rules of law making, hierarchical ordering of norms constituting a given system and apparatus of coercion enabling effective enforcement of established laws.1 Due to the lack of the above-mentioned elements defining the legal system, the key issue of international law is to determine whether a given norm is in fact a norm of international law. The thing that in most legal systems is not a matter of attention of lawyers (primarily due to the existence of a specific catalogue of sources of law and rules how to create norms) in case of international law it becomes a sine qua non condition for further consideration. The norm of international law will always be only the norm which states – the sovereign subjects of this system – recognize as law.
As David Kennedy wrote,2 the debate about sources of international law usually revolves around the four classical sources contained in Article 38 of the Statute of the International Court of Justice. This article is treated as a popular catalogue of sources of international law and as such is the starting point for most of the considerations in this topic.3 Importantly, Article 38 of the Statute of the ICJ is not an universally binding catalogue. In theoretical considerations it is only ancillary in nature, as it is addressed to the Tribunal, indicating which sources of international law should be taken into account when resolving cases. These sources, according to Article 38 of the Statute of the ICJ are: first – international conventions; secondly, international custom; thirdly – general principles of law recognized by civilized nations; and fourthly – as an auxiliary means of establishing norms of law – court judgments and opinions of the best experts in public law of different nations.4 It should be noted that the ICJ itself in its case-law emphasized the importance of Article 38 of the Statute as a starting point for considering sources of international law.5 At the same time it should be noted that among the sources of law indicated in Article 38 of the ICJ Statute there are no sources such as unilateral acts of states and international organizations.6 Although in international law the sources of law are not hierarchical, it’s a common opinion among international lawyers to recognize international agreements and international customs as the main and most important sources of law. As W. Czapliński and A. Wyrozumska wrote, ‘formally sources are of equal importance in international law. However, it is necessary to take into account the specificity of the sources. This specificity suggests the need for a different treatment of general principles of law, because their main function is to fill a gap in customary law or in an international agreement, so they are subordinate (subsidiary) to agreement and custom. This means that in the event of a conflict between an agreement and a general rule of law, the (explicit) contractual norm will prevail.’7

2. International agreements
Currently an international agreement is the most commonly used instrument for creating norms of international law.8 The increase in the significance of international agreements in the last hundred years is most often associated with the intensive development of international relations and the requirement for specificity and detail in the regulation of new problems, to which common law often does not apply.9 An international agreement, like other concepts in the field of international law, has no single, precise and immutable definition. In the literature, it is usually assumed that an international agreement is a joint statement of will of two or more entities of international law, which produces legal effects (creates rights and obligations) in the area of ​​international law.10 The term ‘international agreement’ is the broadest concept, including terms used in practice and theory of international law, such as treaty, agreement, protocol, pact, convention, statute.11 The use of one of the abovementioned terms in practice usually depends on the type of international agreement being concluded, but this distinction has no legal significance.12 The terms 'treaty', 'agreement', 'pact' or 'convention' are commonly used for international agreements of any content and purpose. "Protocol" is the name most commonly used for international agreements which are designed to amend or supplement earlier agreements. The "statute" is usually called international agreements on the basis of which international organizations or institutions are created. As G. Schwarzenberg rightly pointed out, treaties, conventions, agreements, protocols and other terms for international agreements should be treated as synonyms, since all of them mean the same – a harmonized agreement under international law. 13 It should be noted, however, that attempts were made in the literature to differentiate or even evaluate international agreements depending on the name given to them, but gained no broad support.14
The rapid development of international agreements in the 20th century has revealed the need to codify the law of treaties. As a result, the Vienna Convention on the Law of Treaties of 196915 was created (hereinafter VCLT). For the purposes of the VCLT, the following definition of an international agreement (treaty) has been adopted: an international agreement concluded between States in written form and governed by international law, whether embodied in a single instrument or in two or more related instruments and whatever its particular designation (Article 2 VCLT). As one can see, the definition from the VCLT addresses three aspects of agreements that can be called an international agreement - the subjective aspect (specification of the parties to the agreement), the formal aspect (written form) and the objective aspect (the content of the agreement subject to international law).16 This definition narrows the concept of international agreement to written agreements concluded only between states, excluding the application of the VCLT to other types of international agreements. Of course, the definition contained in the VCLT has only an auxiliary use in theoretical works, because its binding power is limited only to the States Parties to the VCLT. To sum up, for the purpose of further considerations in this paper the following definition of international agreement has been adopted – it is a consistent statement of will of two or more subjects of international law shaping the rights and obligations of the parties in the field of international law, expressed in writing.

3. Definition of a peace treaty

There are various definitions of peace agreements and peace treaties in the literature. Ch. Bell defines peace agreements very broadly: ‘Peace agreements are documents produced after discussion with some or all of the conflict’s protagonists, that address military violent conflict with a view to ending it’.17 This definition, as the author admits, includes not only legally binding agreements – acts resulting from the agreement of the parties, but also UN Security Council resolutions aimed at ending the armed conflict.18 J. Kreutz defines a peace agreement as follows: ‘An agreement concerned with the resolution of the incompatibility signed and/or publicly accepted by all, or the main, actors in a conflict. The agreement should address all, or the central, issues of contention.’19 Unfortunately, this definition lacks the legal aspect of the peace agreement, so it is definitely insufficient. The definition given by L. Vinjamuri and A. Boesenecker is more precise – a peace agreement is ’a formalised legal agreement between two or more hostile parties – either two states, or between a state and an armed belligerent group (sub-state or non-state) – that formally ends a war or armed conflict and sets forth terms that all parties are obliged to obey in the future.’20 This definition also has some disadvantages (such as tautological expression ‘war or armed conflic’"), but what is important, the definition presented by Vinjamuri and Boesenecker contains important elements necessary to explain the concept of a peace agreement. A disadvantage, however, of the above definition is still the insufficient definition of the legal status of peace agreements (peace treaties). From an international law perspective this is a key issue. A peace treaty should in principle be an international agreement. Since it is concluded by subjects of international law (regardless of whether they are states or other entities having treaty capacity) and is intended to regulate their rights and obligations, the conditions necessary for recognition of peace agreements as international agreements are fulfilled. J. Kleffner suggests the following definition: ‘Peace treaties are agreements between parties to an armed conflict which end war or an armed conflict between them’ and adds that ‘Peace treaties are agreements concluded between the parties to an armed conflict that end the state of war or the armed conflict between them […] peace treaties stricto sensu are agreements concluded between belligerent States in written form and governed by international law.’21 The disadvantage of this definition is the functional limitation of peace agreements to end the state of war between its parties. However, peace is something more than just a lack of war. The aim of the peace treaty should not only be to end the state of war between the parties, but also to establish normal or even friendly relations between the former belligerents.
The above considerations lead to the construction of a new, full definition of a peace agreement (peace treaty):
• A peace agreement (peace treaty) is an international agreement concluded by the fighting parties, which aims for the final and lasting conclusion of the armed conflict, the establishment of peace and the restoration of normal relations between the parties.

4. Peace treaty as an international agreement

Following the above approach, any international agreement meeting the criteria set out above, regardless of whether its parties are only states or also other entities of international law, even those with limited subjectivity, might be called a ‘peace treaty’ or a ‘peace agreement’. J. Kleffner puts this problem a bit differently, which suggests that the name "peace treaties" is reserved for agreements concluded between states, and for agreements concluded between states and other entities or agreements which non-states enter into with each other proposes the name "peace agreements".22 However, it seems that this distinction is not very accurate. Firstly, in practice, agreements between countries often include in the name words 'peace agreement' rather than 'peace treaty'. Secondly, the nature of an act is not determined by its name, but by its content. Thirdly, agreements concluded by entities other than States or by these entities and States may be, under international law, full international agreements, and thus, from the point of view of law, they will fall into the same category as treaties concluded between States, even if they are not (due to the nature of their parties) subject to the VCLT regulations. This view is supported by opinions of many scholars.23 Importantly – such regulation is explicitly contained in Article 3 of the VCLT, according to which the fact that this Convention does not apply to agreements concluded between states and other entities of international law or between such other entities of international law does not affect the legal force of such agreements and the application of international law norms arising from other sources (e.g. custom). K. Gałka postulates the use of the category of peace agreements as a broader concept, which includes all of the following: treaties within the meaning of the VCLT, ‘international instruments’ which are not treaties within the meaning of the VCLT, and documents that are not at all acts of international law. 24
Notwithstanding the foregoing, it should be acknowledged that it may often be difficult to determine the legal status of individual peace agreements.25 The particular reason for this last problem is the fact that modern wars are often conducted not by states among themselves, but by states with entities (structures) of unclear international legal status (guerilla, quasi-state separatist organisms, federal states, etc.). Thus, although modern international law allows at least partial international subjectivity of such structures as insurgents or national liberation movements, and thus grants them the opportunity to be bound by international law (above all, it covers norms in the field of humanitarian law, but also includes the right to be a party to a peace agreement), however, each case of this type must be assessed separately.
If one adopts a purposeful and functional definition of peace agreement as an agreement concluded by the parties to an armed conflict, which, irrespective of its name, aims to end the conflict and shape peaceful relations between existing enemies, it can easily be seen that such agreements can be qualified a one of two groups of documents: first of all, acts which are undoubtedly international agreements (concluded only by states) and acts whose legal classification as an international agreement may raise doubts due to the entities appearing as parties. In the overwhelming majority of cases, however, this doubt can be successfully dispelled. In accordance with Article 3 VCLT, the fact that the VCLT applies only to treaties concluded by states with other states and does not affect the existence or validity of other international agreements – those concluded between states and other entities of international law, and agreements which other entities of international law conclude among themselves. The norms of customary treaty law will apply to such agreements, and they are mostly identical to those contained in the VCLT.26 An interesting aspect of the issue discussed here is the situation in which at the beginning of the conflict one (or more) of the parties does not have the status of a state, and during the conflict (and as a result of its course) its international legal status evolves towards full statehood, which is sealed by a peace agreement, under which the legal international subjectivity of the newly created state is confirmed and recognized by the other states participating in the conflict. According to Ch. Bell that was the case with Bosnia and Herzegovina after the conclusion of the Dayton Agreement of 1995.27 However, one should keep in mind that Bosnia and Herzegovina declared independence on March 3, 1992, by April it was recognized by several dozen countries, and in May that year, under Security Council Resolution 755 Bosnia and Herzegovina became a member of the UN.28
In practice there are also documents which, although aiming at ending a conflict, are not peace agreements. These will most often be intra-state agreements between political forces of a given country or region, without the features of an international agreement.29 Not being peace agreements, such documents can be components of the peace process.
The entire category, which comprises of interstate peace agreements (agreements whose legal status as a treaty does not raise any doubts), other types of peace agreements (e.g. peace agreements, to which non-state actors are parties - belligerent or partisans), but also documents with unspecified legal status (as the above mentioned internal acts) may collectively be referred to as ius post bellum. This concept is used in the doctrine of international law, both Polish and Anglo-Saxon, unfortunately there is no consensus on its content. C. Mik draws attention to problems in defining the material scope of ius post bellum and emphasizes the axiological layer of this concept, by stating that ‘in the doctrine of international law it is generally recognized that the guiding principle of the period after the conflict is justice.’30 The same author notes that comprehensive peace agreements, containing provisions related to both the ending of the conflict and the reconstruction of the state and creating conditions for peace are of particular importance for the ius post bellum category.31 C. Stahn stresses the need to move away from the idea that peace should be restored to the status quo antem, in order to understand the ius post bellum paradigm as a necessity to shape a peace agreement that will eliminate the causes of the conflict, and not just heal its effects.32 Considering the above opinions, one should opt for the concept according to which ius post bellum is simply a category covering all norms regarding the transition from the state of war (armed conflict) to the state of peace.

5. Conclusion
To sum up the considerations contained in this article, it should be stated that a peace treaty is an international agreement to which both states and other subjects of international law can be parties. The factor that makes it possible to qualify particular international agreement as a peace treaty is the aim of final and lasting conclusion of the armed conflict, establishment of peace and the restoration of normal relations between the parties. This includes establishment of normal relationships between them (economic, tourist, cultural, etc.). Peace treaties might be concluded by states, as well as by other entities of international law. In international practice, however, there are also documents which, despite the purpose similar to peace treaties, are not international agreements within the meaning of international law (e.g. non-binding political agreements), however such type of non-legal documents can’t be treated as the source of international law.

References:
1. Bell Ch., Peace Agreements: their nature and legal status, American Journal of International Law, vol. 100/2006.
2. Bell Ch., O’Rourke C., Peace Agreements or Pieces of Paper? The Impact of UNSC Resolution 1325 on Peace Processes and Their Agreements, Interantional and Comparative Law Quarterly, vol. 59 (2010).
3. Brandon M., Analysis of the Terms “Treaty” And “International Agreement” for Purposes of Rions Charter registration Under Article 102 of the United Nations Charter, American Journal of International Law, vol 47 (1953).
4. Corten O., Klein P., The Vienna Conventions on the Law of Treaties: A Commentary, Oxford, 2000.
5. Czapliński W., Wyrozumska A., Prawo międzynarodowe publiczne. Zagadnienia systemowe, Warszawa, 2004.
6. Czapliński W., Wyrozumska A., Sędzia krajowy wobec prawa międzynarodowego, Warszawa, 2001.
7. Doktór-Bindas K., Zasada przestrzegania prawa międzynarodowego in D. Dudek (ed.), Zasady ustroju III Rzeczypospolitej Polskiej, Warszawa, 2009.
8. Frankowska M., Prawo traktatów, Warszawa, 1997.
9. Frankowska M., Umowy międzynarodowe. Wprowadzenie do prawa traktatów, Warszawa, 1972.
10. Gamble Jr J., Multilateral Treaties: the Significance of the Name of the Instrument, California Western International Law Journal vol. 10/1980.
11. Gałka K., Szczególna ochrona dziecka w porozumieniach pokojowych in Karska E. (ed.) Prawa dziecka w prawie międzynarodowym, Warszawa, 2013.
12. The General Framework Agreement for Peace in Bosnia and Herzegovina UN document A/50/790 and S/1995/999.
13. ICJ Judgement on Delimitation of the Maritime Boundary in the Gulf of Maine Area, ICJ Reports 1984.
14. Kennedy D., The Sources of International Law, American University Journal of International Law and Policy, vol. 2/1987.
15. Kleffner J., Peace Treaties in Wolfrum R. (ed.), The Max Planck Encyclopedia of Public International Law, vol. 8, Oxford, 2012.
16. Kreutz J., How and when armed conflicts end: Introducing the UCDP Conflict Termination dataset, Journal of Peace Research vol. 47 (2010).
17. Mik C., Kongres wiedeński a współczesne koncepcje ius post bellum in Menkes J. (ed.) Idee normy i instytucje Kongresu Wiedeńskiego – 200 lat później - perspektywa międzynarodowa, Warszawa, 2017.
18. Myers D., The Names and Scopes of Treaties, American Journal of International Law, vol. 51 (1957).
19. Ohrid Agreement of 13 August 2001 available at <http://peacemaker.un.org/sites/peacemaker.un.org/files/MK_010813_Frameword%20Agreement%20%28Orhid%20Agreement%29.pdf>
20. Schwarzenberg G., A Manual of International Law, London, 1967.
21. Sozański J., Prawo traktatów, Poznań, 2008.
22. Stahn C., ‘Jus ad bellum’, ‘jus in bello’, ‘jus post bellum’? – Rethinking the Conception of the Law of Armed Force, European Journal of International Law vol. 17 (2007).
23. Vienna Convention on the Law of Treaties of 23 May 1969, United Nations Treaty Series No. 18232.
24. Vinjamuri L., Boesenecker A., Accountability and Peace Agreements Mapping trends from 1980 to 2006, Geneve, 2007.