Soldiers, Not Soldiers of Fortune

Arthur Traldi
Tuesday, July 19, 2022, 8:01 AM

Denying prisoner of war status to fighters in Ukraine on the grounds that they are ‘mercenaries’ violates international law.

Ukrainian flag (Mr ATM,; CC BY 2.0,

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The conflict in Ukraine has brought a number of innovations to international humanitarian law. One of the least analyzed innovations has been one of the most arcane: Authorities in the breakaway Donetsk People’s Republic, or DPR, are using a rarely studied and even more rarely litigated provision of Additional Protocol I (API) to the Geneva Conventions to charge captured foreign fighters with mercenarism. While some innovations from the Ukrainian conflict may have lasting value, this one should be discarded immediately.

DPR authorities first convicted three foreigners of “mercenary activities and committing actions aimed at seizing power and overthrowing the constitutional order of the DPR” in early June. The men, two U.K. nationals and a Moroccan who reportedly also has Ukrainian nationality, were sentenced to death. (The European Court of Human Rights has indicated that Russia should ensure the sentences are not carried out while the court considers the cases.) In June, U.S. nationals Alexander John-Robert Drueke and Andy Tai Ngoc Huynh were also reportedly taken into DPR custody. After their capture, a Kremlin spokesman asserted that the two men are also mercenaries and are consequently unprotected by the Geneva Conventions. This month, BBC news reported that DPR authorities had charged two more captured British nationals with mercenarism. And just last week, Paul Urey—a British aid worker who Donetsk authorities had also deemed a mercenary—reportedly died in captivity.

Their captors’ approach is mistaken on at least three levels. First, all captured people maintain at least some Geneva Convention protections. Second, the claim that mercenaries should not be provided the full panoply of protections contradicts basic principles of the law of armed conflict. Third, it appears that those international laws that relate to mercenaries do not apply to these cases. For purposes of this discussion, I take for granted that the conflict in Ukraine is an international armed conflict, as various sources agree. DPR authorities, who declared independence from Ukraine in 2014, would surely agree as well.

All Captured People Have Some Protection

The protections afforded to people captured during armed conflicts are set out most thoroughly in the Third Geneva Convention. The United States, Russia, Ukraine, the United Kingdom, and Morocco are all parties to the Third Convention—along with all other states in the world. It is broadly understood to reflect customary international law.

Article 4 of the Third Convention defines a wide variety of types of captured people who are entitled to be treated as prisoners of war, or POWs. Those categories include:

  • Members of the armed forces of a State party to the conflict; 
  • Members of militias or volunteer groups that are part of the armed forces of a State party to the conflict; 
  • Members of other militias or volunteer groups, such as organized resistance movements, provided they are (i) under responsible command, (ii) wear a fixed recognizable sign, (iii) carry arms openly, and (iv) conduct their operations in accord with the laws and customs of war; 
  • Members of regular armed forces who profess allegiance to a government or authority not recognized by the Detaining Power; 
  • Identifiable civilians accompanying the armed forces, such as supply contractors, members of labor units, etc.; 
  • Members of crews, such as of civilian aircraft; 
  • Civilian members of a levee en masse; and
  • Captured persons who are or previously were members of the armed forces of an occupied country.

Some other captured persons are entitled to heightened protections even beyond those afforded to prisoners of war, such as military medical or religious personnel, as established in Article 33.

In some legal systems, the allegations that the fighters in DPR custody are mercenaries may raise a question about whether they are entitled to POW rights. This is because some states are parties to treaties that deny mercenaries POW rights (though as set forth below, the legitimacy of that distinction is questionable). But raising the question, in itself, does not give their captors license to mistreat them, because the Geneva Convention sets out a process for resolving such doubts: Under Article 5, in cases of doubt, a captured fighter “shall enjoy the protection of the present Convention until such time as their status has been determined by a competent tribunal.” In other words, even if a state sought to rely on such a treaty, it would first have to prove in a fair hearing that captured persons were mercenaries. Until then, the alleged mercenaries would be entitled to full Geneva Convention protections.

Captured foreign fighters in the DPR also retain the procedural and humanitarian protections of Article 75 of Additional Protocol I to the Geneva Conventions. Article 75 prohibits both civilian and military agents from committing murder, torture, corporal punishment, mutilation, and outrages against personal dignity against any detained person, POW or not. Procedurally, Article 75 also provides fair trial protections similar to those in the International Covenant on Civil and Political Rights.

While API is not customary international law in its entirety, Article 75 likely applies to people detained by the DPR authorities. Ukraine is a party to API—as are the United Kingdom and Morocco. Therefore, API applies in Ukrainian territory. Also, significant non-party states have endorsed Article 75, suggesting it has achieved customary international law status. For instance, the U.S. Department of Defense Law of War Manual reads:

Article 75 of AP I reflects fundamental guarantees for the treatment of persons detained during international armed conflict. Although not a Party to AP I, the United States has stated that the U.S. Government will choose out of a sense of legal obligation to treat the principles set forth in Article 75 as applicable to any individual it detains in an international armed conflict, and expects all other nations to adhere to these principles as well. This statement was intended to contribute to the crystallization of the principles contained in Article 75 as rules of customary international law applicable in international armed conflict.

If Article 75 is customary law, it applies to this conflict regardless of whether DPR is considered independent from Ukraine (unless DPR is a persistent objector, which it would probably not be able to show).

A state party applying Article 75 could hold a procedurally fair process at the end of which it determined that these fighters are mercenaries, and mercenaries are not lawful combatants. This would expose them to prosecution for participating in the conflict. Soldiers kill and attempt to kill. But when they do so in a manner permitted by international humanitarian law, they cannot be prosecuted due to the combatants’ privilege. Participants who are not lawful combatants have no such protection. However, a state that reached such a holding in these cases would be violating both the law of armed conflict in general and API in particular.

Denying Mercenaries Combatant Status Violates Fundamental Legal Principles

Article 47 of API addresses mercenaries. It reads:

  1. A mercenary shall not have the right to be a combatant or a prisoner of war.
  2. A mercenary is any person who:
    (a) is specially recruited locally or abroad in order to fight in an armed conflict;
    (b) does, in fact, take a direct part in the hostilities;
    (c) is motivated to take part in the hostilities essentially by the desire for private gain and, in fact, is promised, by or on behalf of a Party to the conflict, material compensation substantially in excess of that promised or paid to combatants of similar ranks and functions in the armed forces of that Party;
    (d) is neither a national of a Party to the conflict nor a resident of territory controlled by a Party to the conflict;
    (e) is not a member of the armed forces of a Party to the conflict; and
    (f) has not been sent by a State which is not a Party to the conflict on official duty as a member of its armed forces.

Ukraine is also a party to the Mercenaries Convention, though none of the other relevant states is. The Mercenaries Convention defines mercenaries more broadly than API in three primary ways: It does not require that mercenaries in fact participate directly in hostilities; unlike API, it applies to both international and non-international armed conflicts; and in addition to armed conflicts of all sorts, it applies to “other situations” in which mercenaries engage in “concerted act[s] of violence” aimed at undermining the constitutional order of a state or undermining the territorial integrity of a state. States parties—including Ukraine—undertake to make mercenarism “punishable by appropriate penalties.”

Both definitions of mercenarism are very narrow and therefore unlikely to apply in this situation. But both also problematically state that the distinguishing factor of mercenaries is that they are “motivated to ‘take part in the hostilities’ by a desire for “private gain[.]”

International humanitarian law does not typically use the reason a person or force chooses to participate in a conflict as a basis to differentiate between the rights different categories of belligerents have. The same law applies to all warring parties. Lawyers refer to this as the distinction between the jus ad bellum (law on the use of force) or jus contra bellum (law generally prohibiting the use of force) and the jus in bello (law governing the conduct of hostilities once they have begun). Fighters who are members of a state’s armed forces or fall into one of the other categories set out in Article 4 of the Third Convention are entitled to POW status, regardless of what motivates them to fight or what motivates their political or military leaders to order them to do so. The U.S. Law of War Manual consequently describes attempts to deny mercenaries the protections of POW status on the basis of their motivation as “not consistent with fundamental principles of the law of war.” Practically, allowing belligerent parties to deny protections to fighters who would otherwise receive them on the basis of their alleged bad motivations would risk a race to the bottom because parties to conflicts almost universally assert that their cause is just and their adversaries’ is not.

The only provision with any apparent similarity is piracy, which under the U.N. Convention on the Law of the Sea (UNCLOS) must be committed for “private ends.” But even the piracy analogy fails. First, piracy requires engaging in, or intending to engage in, “illegal acts of violence or detention, or any act of depredation[.]” Neither API nor the Mercenaries Convention has a similar requirement that to be a mercenary someone must intend to violate international humanitarian law. Second, the traditional incorporation of a financial motivation into the definition of piracy is no longer accepted: The financial requirement has been omitted in UNCLOS and, as Douglas Guilfoyle explains, is “now generally dismissed as being a necessary element of piracy.” Additionally, while the definition of private ends is currently unsettled, U.S. courts have held that the term “private ends” simply differentiates between state action and actions by private persons or organizations—it does not require a motive of “private gain.”

These Fighters Do Not Appear to Be Mercenaries

Even if the prohibition on mercenarism in API applies to this conflict, it is highly unlikely to apply to the fighters detained by the DPR—as analyses by Lawrence Hill-Cawthorne and Ilya Nuzov have also explained.

To prove mercenarism, the DPR authorities would have to show that all of the factors set forth above were present. Failure to prove any one factor in the definition of mercenaries would defeat a prosecution. In this case, several API factors appear independently sufficient to bar some or all of the Donetsk authorities’ prosecutions:

  • A mercenary must not be a member of the armed forces of a Party to the conflict;

As Nuzov notes, Ukraine appears to have broadly incorporated foreign fighters into its official armed forces. The applicable legal regime defines foreign fighters as “on contract with the Armed Forces of Ukraine.” The Americans, for instance, were reportedly members of Task Force Baguette, and Rep. Adam Kinzinger has described them as part of Ukraine’s International Legion. The legion is part of Ukraine’s Territorial Defence Forces, which is part of the Ukrainian Armed Forces. This would be sufficient to exclude them from mercenary status.

  • A mercenary must be neither a national of a Party to the conflict nor a resident of territory controlled by a Party to the conflict;

The European Court of Human Rights has considered that both British fighters “are married [to or] live with Ukrainian nationals and consider Ukraine to be their home” and that the Moroccan fighter “moved to Ukraine in 2019 to study in Kyiv.” Other sources have reported that the Moroccan fighter and one U.K. fighter are Ukrainian nationals and the second U.K. national has reportedly resided in Ukraine for four years. Under API, this would categorically exclude them from mercenary status. 

  • A mercenary must be “motivated to take part in the hostilities essentially by the desire for private gain”;

As noted above, this test is problematic and inconsistent with international humanitarian law. However, at least one American fighter does not appear to have been motivated “essentially by the desire for private gain[.]” Huynh was interviewed by a local paper before his departure and explained the conflict in Ukraine was “eating him up inside” and that he had “probably” decided to enlist when he learned that 18 year old Ukrainians were being drafted to serve in the military. Under API, this would be a strong defense against a charge of mercenarism.

  • A mercenary must in fact be promised, by or on behalf of a Party to the conflict, material compensation substantially in excess of that promised or paid to combatants of similar ranks and functions in the armed forces of that Party

As Nuzov notes, Ukrainian law directs that foreigners who join the Ukrainian Armed Forces will be paid the same as members of the Ukrainian Armed Forces. This would be sufficient to exclude them from mercenary status. 

The foreign fighters who have been charged with mercenarism in the Ukrainian conflict do not satisfy the legal definition of mercenaries. Moreover, denying fighters legal protections they would otherwise receive solely based on their purported motivations violates crucial principles of international humanitarian law. These prosecutions should be abandoned, and the fighters should be provided with the full protections of the Third Geneva Convention.

Arthur Traldi serves as Senior Consultant at Lexpat Global Services; Senior Fellow at American University's Program on Technology, Law, and Security; Senior Counsel at the Louis D. Brandeis Center for Human Rights Under Law; and adjunct professor at Villanova University Charles Widger School of Law. He previously served as a prosecutor at the International Criminal Tribunal for the former Yugoslavia and in Chambers at the International Criminal Tribunal for Rwanda.

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