The Evolution of Neutrality in Contemporary International Law
I. Introduction
The law of neutrality is a complex element within contemporary international law. From traditional point of view, neutrality was closely linked to the legality of war and was understood as a legal status allowing third States to remain outside of armed conflicts while remaining equal relations with belligerents. This classical concept was developed at a time when war was considered a legitimate way of conducting international relations or different disputes from international matter. However, the adoption of the United Nations Charter fundamentally changed this legal landscape. Due to the prohibition of use of force, enshrined in Article 2(4) of the Charter of the United Nations, the normative framework in which neutrality operates transformed. Consequently, neutrality has not disappeared, but it has been significantly reshaped in my opinion. And that is what this paper will examine, how neutrality functions under modern international law, focusing on the interaction between neutrality and the UN charter, and furthermore I decided to illustrate these developments through one of the most influential actors in modern diplomacy - United States of America.
II. Classical Neutrality and the Legality of War in Traditional International Law
Under classical international law, neutrality was based on the premises that States engaged in war were exercising their lawful right. Third states were therefore entitled to remain neutral and were expected to refrain from participating in hostilities. In return, the states engaged in armed conflict were required to respect the rights of neutral states. If I have to say it with my words, neutrality is like legal personality, it gives rights as well as obligations. The international legal framework requires neutral states to abstain from military involvement and treat the engaged parties in armed conflict impartially, while the conflicted States are obliged to respect the neutral territory and commerce. This system was reflected in customary international law and later codified in the Hague Conventions from 1907. Furthermore, as I mentioned, the classical law of neutrality assumed that wars were legally neutral events, meaning did not judge which side was right or wrong. The purpose of the right of neutrality was to deescalate the already existing conflicts and to protect states that choose not to participate. This legal framework made sense in a world where war was an accepted instrument of national policy.
However, the two World wars demonstrated the destructive consequences of this approach and contributed to the development of a new international legal order based on collective security. The adoption of the United Nations Charter in 1945 marked a turning point in international law. Article 2(4)of the Charter prohibits the threat or use of force against the territorial integrity or political independence of any State. This provision undoubtedly reflects a fundamental shift from a system that tolerated war to one that seeks to prevent it. War is no longer regarded as a lawful legal status governing international relations, except in cases where such conducts can be interpreted as self-defence and potentially can be justified, as I am referring to Article 51of the United Nations Charter. The change has direct implications for the law of neutrality. If the use of force is generally unlawful, then it becomes difficult to justify treating all parties to a conflict equally. A system that demands strict impartially between as aggressor and a victim appears incompatible with the core principles of the UN Charter if we take them under consideration. As a result, many scholars have argued that neutrality, at least in its traditional form, cannot fully survive the United Nations ideas way of regulating international relations.
III. The Continued Legal Validity of Neutrality under International Treaties and ICJ Practice
Despite these arguments, neutrality has not been fully abolished. The Hague conventions from 1907, which emphasise on jus in bello, remain in force and many States rely on neutrality as a legal concept. Furthermore, the Geneva Conventions of 1949 and their Additional protocols explicitly refer to neutral States and regulate their rights and obligations in armed conflicts. These treaties demonstrate that neutrality continues to play a role in international humanitarian law, particularly in relation to the protection of victims in armed conflicts. Additionally, the highest judicial institution in the world, The International Court of Justice, has also confirmed, based on its practice, the continued relevance of neutrality. In its advisory opinions and judgments, the Court has recognised that neutrality remains part of international law, but it must be applied in conformity with the UN Charter. This approach reflects a broader understanding that neutrality has not disrespected but has been transformed by the prohibition of the use of force. One of the key legal developments affecting neutrality is the recognition that the prohibition of the use of force has an erga omnes character. This means that all States have legal interests in its observance, regardless of whether they are directly affected by a particular conflict. When a State violates this prohibition, it does not merely injure the victim State but undermines the international legal order. As a result, third States are no longer entirely free to remain indifferent. Modern international law also recognises that serious breaches of fundamental rights, such as aggression, trigger specific obligations for third States. These includes the duty not to recognise situations created by unlawful uses of force and the duty not to provide aid or assistance in maintaining such situations. These principles are reflected in the Articles of Responsibility of States for internationally Wrongful Acts (ARSIWA) and have been affirmed by international courts and tribunals. Consequently, this creates a tension between traditional neutrality and contemporary international law. On the one hand, neutrality requires non-involvement and impartially. On the other hand, international law prohibits States from supporting or legitimising unlawful situations. In practice, this means that neutrality can no longer be understood as strict equality between belligerents in all circumstances.
This tension becomes particularly clear in cases where one State is clearly responsible for an unlawful use of force under the provisions of United Nations Charter and even historical international treaties, like The Kellog – Briand Pact from 1928. In such situations, treating the aggressor and the victim equally may undermine the prohibition of use of force. For instance, maintaining normal economic relations with an aggressor State may contribute to the continuation of an illegal occupation or armed conflict. Maybe it’s important to note that Article 2(5) of the United Nations Charter explicitly says that all members shall give the United Nations every assistance in any action it takes in accordance with the Charter and shall refrain from giving assistance to any state against which the United Nations is taking preventative or enforcement action. Contemporary international law therefore allows, and in some cases requires, third States to differentiate between the parties to a conflict. This does not necessarily mean that third State must provide military assistance to the victim State. Rather, it means that they may lawfully impose sanctions, restrict diplomatic relations, or otherwise distance themselves from the aggressor without violating international law.
In my opinion, it’s important to mention that after Article 2(4)imposes an obligation on all Member States of United Nations to refrain from using force against the territorial integrity or the political independence of another State, war cannot be interpreted longer as legal institute of international law, simply because the Charter prohibits the use of force as it more importantly, the provision, as I mentioned, has an erga omnes identity . In that regard, many questions arise about the position of the right of neutrality in the new system of the international legal framework as many scholars from the legal doctrine have different views. Additionally, the role of the United Nations Security Council further shapes the modern law of neutrality. Under Chapter VII of the Charter, the Security Council has the authority to adopt binding measures to maintain or restore international peace and security. When the Council imposes sanctions or authorises the use of force, all UN Member States are obliged to comply. Article 103 of the UN Charter establishes the supremacy of Charter obligations over the international agreements. As a result, neutrality cannot be invoked to justify non-compliance with Security Council decisions. Even when the Security Council does not act, often due to political disagreements or the use of veto by one of the five permanent Member States of the Council, third states remain bound by general international law. The absence of Security Council action does not revive the classical law of neutrality in its original form. States must still avoid conduct that would assist in maintaining unlawful situations created using force
IV. The Transformation of United States Neutrality Practice
Now I will analyse how the practice of the United States provides the clearest example of how neutrality operates in contemporary international legal system. Historically, the United States declared neutrality, particularly during the nineteenth and early twentieth centuries. U.S. neutrality laws tried to keep the country out of European conflicts and reflected the classical understanding of what neutrality is, as such practice dates from the establishment of Monroe doctrine. However, U.S. practice changed significantly during the Second World War and the political development from diplomatic aspect of the UN system. Even before formally entering the war, the United States adopted measures such as the Lend-Lease program, which provided material support to States fighting against the Axis powers. Therefore, this could be interpreted as the start of strict neutrality and reflected a growing recognition on the fact that equal treatment of all belligerents was neither morally nor legally appropriate in cases of aggression. In the post-war period, U.S. practice has consistently demonstrated a conditional approach to neutrality.
It is noticeable that the United States has frequently provided political, economic, and military assistance to States it considers victims of unlawful aggression while imposing sanctions and restrictions on States it regards as aggressors. This approach has been evident in numerous conflicts and is justified by referring to the UN Charter and the prohibition of the use of force. Importantly, the United States does not view this practice as a violation of international law. Instead, it argues that assisting an aggressor would itself be unlawful and that neutrality cannot be used as a shield for conduct that undermines collective security. This position aligns with the broader international legal understanding toward prioritising the UN Charter over traditional neutrality rules. U.S. practice also demonstrates that neutrality today does not require military involvement. The United States often supports victim States through non-military actions, such as economic aid, diplomatic backing, and sanctions against aggressors. These measures are seen as consistent with international law and, in some cases, as necessary to uphold the international order, as many officials. Evidently, this approach has influenced the practice of other States as well as international organisations, this does not mean that neutrality has lost all meaning in contemporary sense but rather had a reform in order to adapt to the new geopolitical behaviours by actors from the international society in nowadays.
V. Conclusion
In conclusion, neutrality is still a recognised concept in international law, but its content and application have undoubtedly changed significantly since the adoption of the UN Charter. Neutrality can no longer be understood as absolute impartiality between belligerents. Instead, it operates within a legal framework that prioritizes the prohibition of the use of force, the maintenance of international peace and security, and the collective interests of the international community. The contemporary concept of neutrality allows third states to refrain from direct participation in hostilities while still allowing lawful measures against aggression to be taken. This kind of approach not only reflects a balance between the desire to stop conflicts from starting and escalating, but also the need to uphold fundamental principles of international law. The practice of the United States, on the other hand, illustrates how neutrality has evolved from a classical right enshrined in provisions from international legal sources, into a conditional concept shaped by the UN Charter and the realities of contemporary international relations.
Author: Boris Atanasov (Law student at Sofia University and Global Law student at the University of Turin)
E-mail: borisatanasov22@gmail.com
LinkedIn: Boris Atanasov
