The So-Called Principle of Equal Treatment of Belligerents by the Neutral State

Conventional legal wisdom says neutral States owe belligerents equality of treatment (see for example here, p. 282–84, here, p. 237, and here, p. 466). This is largely inaccurate, however. What’s more, it is astonishing how persistently some cling to this erroneous view.

To be more precise, the error consists in presenting this precept of equality of treatment as a general principle of the law of neutrality. At most, it is but a special principle of neutrality law. Indeed, the neutral State does not owe belligerents equality of treatment in all its behaviors, but rather owes such equality only in special matters, according to a particular norm of the law of neutrality (something that Josef Kunz had already (and perspicaciously) noted (p. 218)). In other words, equality does not flow from a norm of general international law, but from a series of special rules of the law of neutrality within this body of general law. Outside of these special rules, it does not apply.

When the Principle of Equal Treatment Does Not Apply

The law relating to war on land limits neutrality to duties (and rights) concerning military support to belligerents. In contrast, maritime neutrality primarily concerns trade, as one can see through blockades, contraband, and prizes. This means that in land warfare, the law of neutrality does not govern a whole series of relationships between the neutral State and the belligerent. Thus, the neutral State can freely trade with belligerents and it is neither obliged to ensure a normal flow (i.e., courant normal: there is no obligation to retain the same trade volumes as prior to the armed conflict) nor to maintain equality between belligerents (i.e., it can trade with one belligerent and not the other, etc.).

Providing war information and war materials is, of course, prohibited. But the law does not oblige a neutral State to treat belligerents equally in relation to jus ad bellum. A neutral State can, for example, qualify a belligerent as an aggressor, and furthermore, it need not ensure political or moral equidistance between belligerents in its official communications. The neutral State is also not required to intervene to ensure the press portrays each belligerent in any particular light.

The neutral State could curb its trade with one belligerent (and can do the same for “moral” neutrality), but this would only be a policy of neutrality, as the law of equal treatment does not apply in non-military matters. Because neutrality does not impose rules of conduct in non-military matters, neutral States owe belligerents no duty of equal treatment in this respect.

Let us now turn to matters governed by the law of land neutrality, that is, to any measure of military assistance, whether direct (e.g., the delivery of arms) or indirect (e.g., the provision of credits for the purchase of arms). Here again, the principle of equal treatment does not generally apply, and strict duties of abstention bind neutral States. A duty of abstention means a neutral State cannot, for example, deliver arms equally to both parties to the conflict, thereby ensuring compliance with the law of neutrality by claiming impartiality. On the contrary, the neutral State must refrain from delivering such arms to any belligerent. In other words, there is equality of treatment only in a negative form, namely the duty to apply the principle of abstention equally to all belligerents. Given the principle does not extend to the positive aspect (i.e., equal delivery to all belligerents), it is the principle of abstention—as qualified by equality—which governs the matter, not the broader principle of equality.

In short, the principle of equal treatment has no independent standing either in matters not covered by the law of neutrality (because it is inapplicable) or in the area covered by neutrality (because the duty of abstention qualifies it).

These observations extend to other matters governed by the law of armed conflict (LOAC) and are therefore directly linked to the belligerent State. Thus, a neutral State may send medical units or hospital ships to the theatre of armed conflict (see, e.g., First Geneva Convention of 1949, art. 27 (relating to personnel of relief societies of a neutral country); Second Geneva Convention of 1949, art. 25 (relating to neutral hospital ships)). However, the relevant rules of LOAC only authorize such action by the neutral State; they do not negate its duties of neutrality. For example, the law—for obvious reasons—always permits humanitarian aid, even if such aid affords one belligerent a military advantage over another belligerent.

On the other hand, LOAC does not require the neutral State to treat belligerents equally in this respect. For example, a neutral State need not send the same amount of humanitarian aid to both or all belligerents. Such a rule would make little sense, because the neutral State would most likely send humanitarian aid based on where it seems most urgently needed, not on abstract principles of equal treatment. Therefore, in matters directly related to the armed conflict, the same rule described above applies, eliminating the equality obligation in such areas.

When the Principle of Equal Treatment Does Apply

This is not to say the principle of equal treatment never applies. Specific norms of neutrality law trigger its application and also provide for its implementation. An example is Article 9 of the Hague Convention V of 1907, which states, “Every measure of restriction or prohibition taken by a neutral Power in regard to matters referred to in Articles 7 and 8 must be impartially applied by it to both belligerents.”

Article 7 provides that a neutral State is under no obligation to intervene to stop or diminish any arms trade with the belligerents conducted by private actors located within its territory. The neutral State’s non-intervention in this trade does not violate its duties of neutrality. However, Article 9 provides a caveat: if the neutral State decides to intervene to restrict or regulate this export, the State must apply these restrictions equally.

At the same time, Article 6 of the Hague Convention XIII of 1907 prohibits the export of arms by the neutral State. Nowadays, States strictly control private arms exports, most often via the grant of export licenses. When such licenses are required, the State cannot grant them without breaching its neutrality duties. By granting such a license, the State is considered itself to export the arms and falls under the prohibition in Article 6. The rigid division between private and State weapons transfers that underlies the Hague law is outdated, as one scholar had already noted by the end of the Second World War (see Maurice Bourquin, Vers une nouvelle Société des Nations, p. 145–46).

Another area where a rule of impartiality exists concerns the acts that a neutral State allows military vessels to conduct in its internal or territorial waters: innocent passage; supplies; and repairs (see 1994 San Remo Manual on International Law Applicable to Armed Conflicts at Sea, art. 20 (“Subject to the duty of impartiality … .”); Hague Convention XIII, art 9 (“A neutral Power must apply impartially to both belligerents the conditions, restrictions, or prohibitions made by it in regard to the admission into its ports, roads, or territorial waters, of belligerent warships or of their prizes”)). Other expressions of equal treatment are a matter of neutrality policy, not law.

Conclusion

In summary, one can conclude that scholars and practitioners grossly overestimate the importance of the principle of equal treatment of belligerents. States will most often apply this principle as a policy of voluntary neutrality, likely so as not to catch the eye of a belligerent that might otherwise complain of discrimination.

In law, the principle of equal treatment has no application to matters that are not covered by the law of neutrality, such as trade (war on land) or political solidarity. Likewise, the principle of equal treatment has no independent standing in areas where the law of neutrality applies—namely military support to belligerents—given its auxiliary relationship to the principle of abstention, which governs the matter.

Furthermore, the principle of equal treatment has no basis in action directly linked to the conflict where the applicable rules do not require it, such as medical aid. Instead, the principle only applies to special areas by virtue of a norm of the law of neutrality, notably in the export of private arms (a category which has almost completely disappeared today) and the treatment of warships in neutral waters. In short, the principle is of limited relevance to the law of neutrality today.

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Robert Kolb is a Professor of Public International Law at the University of Geneva and former legal staff member of the ICRC.

The views expressed are those of the author, and do not necessarily reflect the official position of the United States Military Academy, Department of the Army, or Department of Defense. 

Articles of War is a forum for professionals to share opinions and cultivate ideas. Articles of War does not screen articles to fit a particular editorial agenda, nor endorse or advocate material that is published. Authorship does not indicate affiliation with Articles of War, the Lieber Institute, or the United States Military Academy West Point.

Photo credit: U.S. Army, Sgt. Crist Joseph