Despite its importance, there are many open questions regarding the core definition of what a permanently neutral state is. In the clearest situations, like the case of Switzerland or Austria, and Malta, permanent neutrality is based on a constitutional law norm confirmed by the international community. However, there are other cases where the situation calls for further analysis, as neutrality was declared only by a parliamentary resolution, without wide-reaching international recognition.

Does defining permanent neutrality even matter?

International law is a language between its legal subjects, echoes the widely used metaphor. Sometimes this language is not clear-cut regarding the existence, usage, or meaning of certain terms or their specific content. Just like language, international law is in constant flux. One interesting and decisive example of this is the question of unilateral acts as legal sources, specifically in the field of the law of (permanent) neutrality.

Defining permanently neutral states under international law (and constitutional law and European Union law) has important consequences. A permanently neutral state is obliged to take a stance of neutrality in case an international armed conflict breaks out between other countries, thus taking up a legal status of neutrality, which obliges the neutral state to abstain from the armed conflict and the parties to the armed conflict to respect its decision. The legal status of neutrality obliges both the neutral and the belligerent states to apply the corpus of the law of neutrality and its norms addressed to their situation as special norms (for instance the V and XIII Hague Conventions from 1907, or the Geneva Conventions of 1949). This has a legal effect on maritime and land commerce, navigating in sea waters, prohibition of contraband, volume of trade between the countries, obligations under international humanitarian law (internment and treatment of belligerent troops on neutral territory, confiscating war material on neutral territory), etc.

A permanently neutral state may leave its neutrality behind, but it must first modify its legal status, which may be protected under international law (such as an international agreement, like Article 3 of the Second Treaty of Paris from 1815 in case of Switzerland) or constitutional law (for example, Art 3 of the Constitution of Malta) Therefore, the question of what precisely permanent neutrality is has important consequences.

In case of Switzerland, its permanent neutrality was confirmed by the international community in the above-referenced Second Treaty of Paris and is mentioned in its constitution (Art 173 and Art 185 of the Constitution of Switzerland). The Constitution of the Republic of Moldova declares permanent neutrality, and UNGA Resolution 72/282 (2018) confirmed its neutrality. The permanent neutrality of Turkmenistan was also confirmed by the international community through a UNGA resolution and is declared in the second article of its constitution.

There is an important distinction to be made between permanently neutral states and states simply following a foreign policy of neutrality, as in the second case, there is no international law or constitutional law norm obliging the state to stay neutral in case an international armed conflict breaks out between other countries. They simply follow a policy of neutrality, which means their neutrality is guaranteed only in the political landscape, which may change more easily than constitutional law or international law obligations. There is no legal basis for international responsibility if they change their policy without modifying any legal norms.

There are countries, however, that can be placed in a grey zone between permanently neutral states and states following only a neutral foreign policy. Serbia and Ukraine have only adopted parliamentary resolutions regarding neutrality. In case of Ukraine, being in an armed conflict and not calling upon neutrality, the question has mostly theoretical significance. However, in case of Serbia, the question arises, whether Serbia is a permanently neutral country, having more rights and obligations than Ireland, for instance, or if its legal status is closer to that of Switzerland or Austria. This piece  will examine this question below.

Open questions regarding unilateral acts of states

What does theory say about unilateral declarations? For a long time (and we can say even today to some degree), international law doctrine and practice were not in harmony in this field of international law. There is difficulty in defining them and establishing a universally accepted theory regarding these sources. Article 38 of the Statute of the International Court of Justice (ICJ) does not include unilateral acts of states in the list of norms applied by the court. According to Georg Jellinek, the legal force of international law stems from the self-restriction of states, for example, through signing international treaties. The state may restrict itself by its own unilateral declaration as well. Examples of these include declarations of war, state recognition, declarations under treaty law like reservations, accepting the jurisdiction of an international court, or declarations of neutrality.

“Unilateral acts can produce legal effects in international law”, stated the ICJ decades ago. Even though the Statute of the ICJ does not reference unilateral acts, they exist, and have (significant) legal effect, as the above-mentioned examples make this clear as well. Even the jurisprudence of the Permanent Court of International Justice (PCIJ) and of the ICJ referenced unilateral acts as sources in multiple decisions (Legal Status of Eastern Greenland (Denmark v. Norway), PCIJ; 1933, Nuclear Tests (Australia v. France), Judgment, ICJ, 1974 and a parallel case, Nuclear Tests (New Zealand v. France), Judgment, ICJ, 1974; Obligation to Negotiate Access to the Pacific Ocean (Bolivia v. Chile), Judgment, ICJ, 2018).

The Federal Constitutional Law on the Neutrality of Austria (1955) is a unilateral declaration of Austria that was confirmed by the USA, UK, France and the Soviet Union, thus gaining international recognition.

Therefore, unilateral declarations are sources of international law, and there are examples in force of this in the field of international law as well. It is, however, an important question whether they only bind the state issuing the declaration (auto-normative) or other states as well (hetero-normative). In the latter case, the confirmation of other states (or of the international community) is needed (as it was the case of the permanent neutrality of Austria in 1955). Another question about unilateral acts is whether they aim to bear legal obligations. In case of declarations of neutrality, the answer is clearly yes. Issued declarations may not be revoked in an arbitrary manner (depending on its content and how much the other legal subject counted on the declaration and whether there is a fundamental change of circumstances).

A further criterion is whether they intend to oblige the state to take up the legal status of permanent neutrality or just political neutrality.

The International Law Commission issued Guiding Principles applicable to unilateral declarations of States capable of creating legal obligations in 2006, which state that “By virtue of their functions, heads of State, heads of Government and ministers for foreign affairs are competent to formulate such declarations. Other persons representing the State in specified areas may be authorized to bind it, through their declarations, in areas falling within their competence”. In my opinion, this includes national parliaments as directly elected organs of the state and having the competence to issue such declarations. The guiding principles further state that in case of doubt of the scope of obligations stemming from the declaration, a restrictive interpretation shall be applied, weighing the text of the declaration, together with the context and circumstances of its formulation.

Declarations may be addressed to specific states or to the international community as a whole. They may be issued in writing or declared orally. Their binding character is based on the principle of good faith. The Maritime Delimitation in the Caribbean Sea (Nicaragua v Honduras), Judgment, ICJ, 8 October 2007 case showed that even the absence of protest may be relevant.

After the conceptual analysis, a specific examination of declarations of permanent neutrality is necessary for the purposes of this post.

Parliamentary resolutions and defining permanent neutrality

Therefore, in my opinion, national parliamentary declarations regarding permanent neutrality may in fact oblige other states and may establish a status of permanent neutrality under international law. However, there are specific conditions that need to be met first.

• Did the parliamentary assembly have the power to issue the declaration of permanent neutrality?
• Did the declaration state that the intention is to establish permanent neutrality, or is this aim clearly incorporated in its text?
• What was the context and what were the circumstances of the adoption of the declaration?
• Did the international community or other states confirm the declaration of neutrality?
• It is important that in some cases even the absence of protest may be relevant in recognizing a permanently neutral status, but this must be analyzed case-by-case.

The Resolution of the National Assembly on the protection of sovereignty, territorial integrity and constitutional order of the Republic of Serbia states in its 6^th article, that “the National Assembly hereby declares the neutral status of the Republic of Serbia towards effective military alliances until a referendum is called, at which the final decision on this issue will be made”. Sovereignty is also connected to the question of a state being neutral.

Furthermore, another resolution of the National Assembly of the Republic of Serbia (2007), the decision on the Protection of Sovereignty, Territorial Integrity and the Constitutional Order of the Republic of Serbia (“Military Neutrality Declaration”) Published in the Official Gazette of the Republic of Serbia, No. 125/2007 states the National Assembly of the Republic of Serbia must adopt a decision declaring the military neutrality of the Republic of Serbia vis-à-vis existing military alliances, until a possible referendum is held to make a final determination on the matter. The text references in the same article Nato and Kosovo, expressing that it is connected to the policy of military neutrality of Serbia.

Article 99 of the Constitution of Serbia states in paragraph 4. that the National Assembly has the right to decide on war and peace). The texts do state that Serbia declares neutrality, but also it binds the final decision to a future referendum. However, it is declared for an indefinite period towards all military alliances and thus states as well. It could be interpreted as permanent neutrality, but as neutral policy as well. There was no confirmation by the international community.

The Declaration of State Sovereignty of Ukraine states in its 9^th Article that “the Ukrainian SSR solemnly declares its intention of becoming a permanently neutral state that does not participate in military blocs and adheres to three nuclear free principles: to accept, to produce and to purchase no nuclear weapons.”

Ukraine was becoming an independent state during the collapse of the Soviet Union. For the sake of this article, we will assume that the parliament had the power to assume a declaration of neutrality. The text clearly states, “permanently neutral state”, which means it is not merely a policy of neutrality, but a permanent neutral status under international law.

In both cases, it could be argued that the resolution was intending to establish permanent neutral status, although the Serbian National Assembly seemed to give the final decision to the people by way of referendum. Neither, however, were confirmed by international agreements. The week point of the argument for permanent neutrality is the lack of recognition, although it could be seen as an absence of protest. There is no clear answer until an international legal forum assesses the question, or the situation changes fundamentally. In case of Ukraine, this question seems more to be a historic one, while in case of Serbia, it bears more practical significance. In some cases, unilateral declarations still remain to be open to more interpretations.

Languages are constantly in flux

Languages are constantly in flux – as stated in the introduction; they always develop. So does international law as well. This can be seen in unilateral acts and permanent neutrality. The law of neutrality, unfortunately, is currently developing dynamically due to ongoing international armed conflicts. In my opinion, national parliamentary resolutions are unilateral acts, and thus permanent neutrality may be based upon them, however, the constitutional law of the country in question may be relevant in assessing this question. Providing a confirmation of neutrality by the international community builds a stronger case for actual permanent neutrality, but parallel interpretations exist. This, however, only shows that international law is not a dead language, but a living one.

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Árpád Lapu is an assistant research fellow at the Károli Gáspár University of the Reformed Church in Hungary. He was a policy adviser on constitutional issues at the European Parliament between 2019-2024. Between 2024 and 2026, he worked as an advisor at the Ministry of European Union affairs, and between 2017 and 2019, as an adviser at the Ministry of Justice of Hungary, conducting comparative constitutional, international law and EU law analyses. He has earned his JD at the Pázmány Péter Catholic University in Hungary, has a BA in international relations from the University of Szeged, and an MA in European and international administration from Andrássy Gyula German Speaking University in Budapest. He has completed an LLM in international law at the Catholic University of Louvain (UCLouvain). His field of research is neutrality and non-participation in armed conflicts in international law and constitutional norms regarding permanent neutrality. He has written publications regarding the future of the EU ETS system of the European Union, institutional reform proposals, and policies of the EU, and conducted research in the field of social sciences.