Evolution of the Law of Neutrality

In international humanitarian law (IHL), the law of neutrality defines the relationship between States engaged in an armed conflict (belligerents) and States not involved in hostilities (neutrals.) The concept of neutral States in times of conflict is an ancient one, dating back to Ancient Greece and Rome.1Poddighe E, “Neutrality, Political, Greece and Rome” [2012] The Encyclopedia of Ancient History It is based on the idea that certain States can remain neutral during times of armed conflict and are thus not bound by the obligations of the warring parties. Over the centuries, the law of neutrality has evolved to take into account the changing realities of foreign affairs and the conduct of nations and the demands for international peace and security. This article explores the evolution of the  law of neutrality and the current ambiguities surrounding it.

18th and 19th Centuries

 By the end of the 18th century, the doctrine of the law of neutrality divided States into two possible categories: belligerent States and neutral States (those unrelated and unaffected by the matters of the belligerents).2Twiss T, The Law of Nations, Considered as Independent Political Communities: On the Rights and Duties of Nations in Time of War (The Clarendon Press 1875)- Pg. 267 Neutrality was dependent upon the existence of a state of war which was not a factual determination but an indication or declaration of a position adopted by one of the belligerent States. Non-participant States were not competent to assess the nature of hostilities and a legal state of war only existed when one of the belligerent parties said so.3Brownlie I, International Law and the Use of Force by States (Clarendon Press 1963) This is also reflected in the legal opinion given to the British Crown in 1862 when Ecuador engaged in an armed struggle to free Peru from Spanish control: “Neutrality according to the law of nations, means the neutrality of one State, as between two or more States who are at war between themselves; and has no bearing upon a state of peace…”4“A D McNair (ed) International Law Opinions vol III (CUP, Cambridge 1956) 152.” This meant that States could declare war without the use of any actual force or hostilities and, conversely, not declare war despite using force and declare it to be a reprisal.5John B Moore, Digest of International Law vol VII (US Government Printing Office, Washington DC 1907) 153. This allowed them to avoid the application of many rules under IHL and non-participating States would not be considered neutral parties.

On the other hand, non-participants did not have the same legal authority to declare themselves neutral as belligerents did to declare war. Hence, a State’s ability to remain neutral in times of hostilities was determined by a particular State’s strength and strategic importance. It was a question of sovereign prerogative that determined whether a State could assert its neutrality, rather than a question of law.  Only if the belligerents decided to regard them as neutrals, through the mechanism of recognition, were non-participant States given neutral status.

At a time when States had the absolute right to resort to war, this relationship between war and neutrality was of a reciprocal nature, where the duty of the impartial (neutral) State was quid pro quo for the belligerent not attacking them, and the belligerent tolerating neutrals trade and commerce with the enemy.6Williams Jr W. L, “Neutrality in Modern Armed Conflicts: A Survey of the Developing Law” [1980] College of William & Mary Law School William & Mary Law School Scholarship Repository

Codification and the 20th Century

 The codification of the law of neutrality can be seen in the Hague Conventions III, V, and XIII of 1907. The Hague Convention III, which aimed to ensure that hostilities are not initiated without due warning,7Preamble removed the uncertainties caused by the state of war doctrine by defining when the law of neutrality applied. Article 2 of the Convention suggests that all non-participating States are deemed to be neutral upon the outbreak of hostilities whether or not they are aware of the existence of a war.8Upcher J, “Ch.1 Neutrality, Non-Belligerency, And The Prohibition Of The Use Of Force,” Neutrality in contemporary international law (Oxford University Press 2020)

Similarly, Article 6 of Convention XIII places a duty on neutral States to not supply, directly or indirectly, warships, ammunition, or war material of any kind. Supplying this material constitutes a violation of a neutral duty, even if provided to belligerents on an equal basis. However, these duties only exist on supplies from the State and not by the private citizens of the neutral State. Similarly, Convention V provides that the neutral State must not permit the belligerent State from moving troops or convoys of munitions of war or supplies across its territory. It must also not allow belligerents to set up communication devices on its territory, or allow the formation of corps of combatants, or the establishment of recruitment agencies, on its territory.9Articles 2,3,4 and 5.

Furthermore, Conventions V and XIII require that all actions and restrictions placed by neutral States must be done so impartially10Article 9 with the object that nothing should be granted to one party which is not allowed to the other party. This is perhaps the most fundamental principle and purpose of neutrality i.e. the demonstration of neutrality by a neutral State towards all warring parties involved in a conflict.

With regards to the rights of neutral States, the Hague Convention XIII provides that “belligerents are bound to respect the sovereign rights of neutral Powers and to abstain, in neutral territory or neutral waters, from any act which would if knowingly permitted by any power, constitute a violation of neutrality.”11Article 1 Similarly, Hague Convention V provides that “the territory of neutral Powers is inviolable.”12Article 1

Pre-UN Charter Developments

Historically, the declaration of war and the use of force were considered legitimate expressions of sovereignty; however, this changed with the formation of the League of Nations and the Kellogg-Briand Pact of 1928. The League limited the circumstances in which nations could resort to war, and the Pact obliged States to prohibit war as a matter of national policy. However, both the Kellogg-Briand Pact and the Covenant of the League of Nations operated within the ‘state of war’ doctrine.13Ibid n.5 This meant that even if  hostilities reached the level of war, the law of neutrality would not become operative simply because the nation refuses to classify the situation as a war or make a declaration of war and hence argue a ‘state of war’ does not exist.14Baty T, “Abuse of Terms: ‘Recognition’: ‘War’” (1936) 30 American Journal of International Law 377 For e.g. in 1931 Japan invaded Manchuria without declaring war and hence the rules of IHL and neutrality did not come into play.15H Lauterpacht ‘ “Resort to War” and the Interpretation of the Covenant During the Manchurian Dispute’ (1934) 28 AJIL 43

Qualified Neutrality and Non-Belligerency

At the outbreak of World War II, the USA declared its neutrality in the war in 1939. However soon afterwards the USA chose to assist the Allies without engaging directly in hostilities, by providing naval destroyers and bases to Britain in 1940. Similarly, in 1941, the US Congress passed the Lend-Lease Act to provide defense equipment to countries whose defense was considered vital to the defense of the USA. The USA justified its position using the Pact of Paris saying that States could adopt a position of ‘qualified neutrality’ i.e., that neutral States could now support belligerent States that had been a victim of illegal wars of aggression.16Schmitt MN, “Providing Arms and Materiel to Ukraine: Neutrality, Co-Belligerency, and the Use of Force” (Lieber Institute West PointSeptember 19, 2022) <https://lieber.westpoint.edu/ukraine-neutrality-co-belligerency-use-of-force/> accessed February 18, 2023 This apparently created a third category of States: belligerents,  neutrals, and non-belligerents (States that were not engaged in hostilities but did not assume neutral State duties).

Some scholars such as Dietrich Schindler have gone even further from the USA’s ‘Qualified Neutrality’ position to suggest that since 1945 the law of neutrality is no longer binding on States. Rather it is an optional status in which States may choose between being neutral and non-belligerent.17M. DAJ, Kalshoven F and Tanja GJ, “Transformations in the Law of Neutrality Since 1945,” Humanitarian law of armed conflict: Challenges ahead: Essays in honour of Frits Kalshoven (Martinus Nijhoff 1991)

State practice and proclamations seem to reject the idea that neutrality is an optional position. Thus, it cannot be said that the non-belligerency of a few States in WWII was accompanied by corresponding opinio juris.18Ibid n.5 For instance, when the Arab-Israeli war broke out in 1967, States such as France and USA continued to consider themselves bound by the law of neutrality and were neutral States.19Ibid Similarly in recent hostilities many States have remained unwilling to accept the concept of ‘qualified neutrality’ as suggested by the USA.20Nasu H, “The Future Law of Neutrality” (Lieber Institute West PointJuly 19, 2022) <https://lieber.westpoint.edu/future-law-of-neutrality/> accessed February 18, 2023  Hence confirming that assuming neutral obligations at the outbreak of hostilities is not optional for States.

UN Charter

Article 2(4) of the UN Charter attempted to curb the uncertainties surrounded with the language of war. It outlawed the use of force by States altogether and overcame the deficiency that governments could circumvent the law by simply not calling their military actions war. There are only two exceptions under the UN Charter where force can be used: firstly, when a collective security action has been ordered by the UN Security Council under Chapter VII of the UN Charter  and secondly, in individual or collective self-defense against an armed attack under Article 51 of the UN Charter. 

Effects on Neutrality

The UN Charter resulted in bringing many changes to how the law of neutrality previously applied.  When the UN Charter came into force some writers went as far as contending that by eradicating all references to war or state of war, the Charter not only abolished the legal institution of war but also eradicated all legal doctrines associated with it such as the law of neutrality.21Lauterpacht E, “The Legal Irrelevance of the ‘State of War’” (1968) 62 Proceedings of the American Society of International Law at its annual meeting 58 However, this view does not align with State practice and there is a general acceptance that the law of neutrality continues to apply. The same has also been recognized by the International Court of Justice, that the law of neutrality, even though it is subject to the conditions of the UN Charter, continues to apply to nations.22Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, 1. C.J. Reports 1996, p. 226 -Para 89 Hence, the law of neutrality has been modified and regulated by the UN Charter with regards to when the neutral status of a country can be prescribed or abandoned.

The first effect of the UN Charter is that the neutral status of a country can be overridden when an enforcement measure is taken by the UN Security Council under Chapter VII of the Charter. In such a situation a State can be prevented from remaining neutral and may be incapable of performing its neutral duties. For example, a State cannot invoke neutral duties to prevent movement of troops or movement of UN Special Forces from crossing its territory when acting pursuant to a UN Security Council resolution.23Upcher J, “Ch.1 Neutrality, Non-Belligerency, And The Prohibition Of The Use Of Force,” Neutrality in contemporary international law (Oxford University Press 2020)

Secondly, unlike in the 19th-century, States are no longer free to move between belligerent and neutral status. Previously, the choice to join war and support war was part of the State’s sovereign prerogative; however, the UN Charter now regulates under which circumstances a State can use force  For example, in cases of self-defense, a State can only exchange its neutral status to help the victim of armed attack but cannot provide military support to the aggressor State.24Ibid 5

Furthermore, the recognition of neutrality by a belligerent is no longer relevant after the signing of the UN Charter. The recognition of neutrality was only relevant to determine whether a state of war existed or not, and to assure whether the mutual duties and obligation of neutrality applied between States. However, States now no longer require protection (in the form of a promise from the belligerent) to be protected from being attacked.

Law of Neutrality Today

The law of neutrality today has to be interpreted in a way that accommodates modern State practice and in light of the evolution of international law since 1907. It cannot be justifiably  argued that the law of neutrality remains intact in its original form as laid down in treaties and customs, but rather that those duties are superseded by the provisions of the UN Charter. Hence, States nevertheless have to follow all the neutral duties and obligations in the event of hostilities unless prevented from doing so by a security council resolution. In the cases where the UN Charter is silent or UN mechanisms fail the law of neutrality would continue to apply. Whereas its interpretation and scope continues to evolve through State practice while dealing with modern issues such as cyberwarfare or space warfare, the original obligations of the law of neutrality, such as the obligation not to provide direct military assistance, continue to be operative and part of international law.


The law of neutrality has gone over many changes in the previous centuries. From being akin to a contract between two parties it became the default position at the outbreak of war. After the emergence of the UN Charter, the traditional position of the law of neutrality is greatly subjected to the rules regulating the use of force and when self-defense (individual or collective) can be used. Suggestions by writers and States that neutrality does not apply in today’s world is not a defensible position in international law. As recently noted in Horgan v An Taoiseach et al;

“…there does still exist in international law a legal concept of neutrality whereunder co-relative rights and duties arise for both belligerents and neutrals alike in times of war in circumstances where the use of force is not ‘UN led’.”25ILDC 486 (IE 2003)

The purpose of the law of neutrality has been to minimize the harmful effects of hostilities and further to prevent them from escalating, hence further evolution or interpretation of the law of neutrality while dealing with modern issues has to be done so in harmony with the same purpose.


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Talha Riaz

Muhammad Talha Riaz is a final year BA-LLB student at Lahore University of Management Sciences. He has been the Vice President of Lums law and Politics Society and is currently part of the Lums Law Journal editorial Committee. His areas of interest include Global Governance, International Human Rights Law and Constitutional Law.