Lieber Studies POW Volume Symposium – Military Assimilation and the Third Geneva Convention

by | Feb 22, 2023

Military assimilation

Editor’s note: The following post highlights a chapter of the Lieber Studies volume Prisoners of War in Contemporary Conflict, which will be published 3 March 2023. For a general introduction to this volume, see Professor Mike Schmitt and Major Christopher J. Koschnitzky’s introductory post.

At 143 articles, the Third Geneva Convention relative to Prisoners of War is an imposing and difficult instrument. Efforts to understand and to put its protective obligations into practice often resort to simplifications or generalizations. For example, States’ armed forces frequently reduce the Convention to mnemonics to train prisoner treatment such as the US Army’s “Five S’s,” including “search, segregate, silence, speed, and safeguard.”

For its part, the International Committee of the Red Cross, in its recently updated Commentary to the Third Geneva Convention, identifies more than a dozen “principles” as means to distill the Third Convention’s protections thematically and to clarify their meaning. These principles include the well-known notion of humane treatment, but also less familiar tenets such as “voluntary and informed consent” to medical treatment and military “assimilation.” In the latter respect, the Commentary advises that assimilation, “runs through the Convention as a whole.” (para. 4003). By reducing the Convention’s protections to themes, the ICRC hopes to aid “understanding and application of [its] more technical provisions” (para. 1495).

But reduction also tempts mischaracterization. Alongside the myth that prisoners of war must be paid in Swiss francs, military assimilation—the notion that, for purposes of treatment, prisoners of war are effectively integrated into the armed forces of the detaining power—is a common misrepresentation. In truth, the Third Convention resorts to military assimilation only selectively. It is neither a predominant nor a pervasive feature of the Convention. Misunderstanding on this count not only invites misapplication of its finely wrought and battle tested protections. It also invites excessively broad protective claims likely to undermine consensus on the meaning the universally ratified Third Convention.

Historical Practice

It is true that States have long resorted to military assimilation to regulate the treatment of prisoners of war. Ancient armies employed perhaps the most drastic form of assimilation by absorbing enemy captives into their own fighting forces. By the 19th century, States had largely abandoned enemy absorption, but often found assimilating the treatment standards applicable to their own armed forces a convenient approach to regulating treatment of prisoners of war. Late 19th and early 20th century instruments often assimilated prisoners of war to friendly armed forces for purposes of feeding, clothing, housing, and discipline.

But as States gained experience with these instruments in war, the assimilative approach often unraveled or proved inadequate. In some cases, States even repealed early textual resorts to assimilation. For instance, although the 1899 and 1907 Hague Conventions’ Regulations on land warfare are nearly identical, the latter expressly abandoned the former’s assimilation of the detaining power’s military pay scales for prisoners of war in favor of a standard based on the specific work done (see 1907 Hague IV., art. 6).

Retreat from assimilation extended to the Geneva tradition of the law of war as well. The 1929 Geneva Convention Relative to the Treatment of Prisoners of War resorted to military assimilation for living areas, air quality, and bedding. But it abandoned the Hague Regulations’ full assimilation regime for pay for officers, capping pay at the amount paid by the prisoners’ State of origin (1929 GC POW, art. 23). The 1929 Convention also departed from military assimilation for prisoners’ maximum working hours and labor standards, incorporating the detaining power’s civilian standards instead (1929 GC POW, art. 27).

The 1949 Third Convention

While the 1929 Convention had scaled back military assimilation in these respects, both diplomatic and academic sources indicate that its surviving assimilative provisions accounted for a substantial portion of its failings in the Second World War (p. 44). Thus, States revisited military assimilation at the 1949 diplomatic conference that adopted the Third Geneva Convention. Like its predecessors, the Third Convention employs treatment standards assimilated from armed forces across a range of subjects including quarters, food, clothing, labor, and discipline. Yet, also like preceding efforts, the Third Convention repealed other military assimilative provisions and made only limited and sporadic use of military assimilation overall.

With respect to housing, Article 25 of the Third Convention offers what seems at first glance a fully assimilative approach. It requires that prisoners of war be quartered “under conditions as favorable as forces of the Detaining Power who are billeted in the same area.” Article 25 immediately indicates, however, that even localized military assimilation is not fully adequate and that detaining powers must depart from—or in the words of the article, “shall make allowance for”—the habits and customs of prisoners of war for purposes of housing. Thus, military assimilation is not fully descriptive of the Convention’s approach to prisoner of war quarters.

Article 26 of the Third Convention addresses the historically challenging issue of feeding prisoners of war. The article requires that rations “keep prisoners of war in good health and . . . prevent loss of weight or the development of nutritional deficiencies.” Thus, rather than resort to the prior military assimilation standards of the 1907 Hague and 1929 Geneva Conventions, or even the caloric tables used by First World War supplemental agreements, the Third Convention imposes a results-based standard based on objectively measurable effects of diet on prisoners of war. Further, in light of poor historical experience with prisoners adjusting to the tastes, nutritional qualities, and portions of foreign cultures, the Convention requires the detaining power to take account “of the habitual diet of the prisoners.” In this respect the Convention again expressly rejects military assimilation, particularly when there is great dietary or nutritional variance between captors and captives.

Addressing penal and disciplinary sanctions generally, Third Convention Article 82(1) retains military assimilation. Like its predecessors, the article indicates prisoners of war are “subject to the laws, regulations and orders in force in the armed forces of the Detaining Power.” Article 102 also requires that prisoners of war be tried and sentenced only by “the same courts according to the same procedure” as the detaining power’s armed forces. Similarly, Article 87(1) of the Third Convention limits punitive sentences to penalties applicable to “members of the armed forces of the [Detaining] Power who have committed the same acts,” effectively assimilating military penal schemes. Meanwhile, Article 88 resorts to an unfiltered form of military assimilation, insisting that punishments of non-commissioned officers, officers, and women prisoners of war accord with the treatment of their detaining power counterparts.

Yet Article 87(2) softens military assimilation with respect to disciplinary and penal matters by directing States to account when fixing punishments for the fact that prisoners of war owe no allegiance to the detaining power. Article 95, addressing pretrial confinement, includes a similarly qualified resort to military assimilation. Under the article, a detaining power may only subject a prisoner of war to close, pretrial confinement when “a member of the armed forces of the detaining Power would be so kept.” But the article also permits close, pretrial confinement of prisoners of war “if it is essential in the interests of camp order and discipline,” even if such confinement would not be available for a member of the Detaining Power’s armed forces.

Many other provisions of the Third Convention, detailed fully in my chapter of the Lieber Studies Prisoner of War volume, repeat the pattern of a highly discriminatory resort to military assimilation to protect prisoners of war. The chapter clearly illustrates that the Convention regulates evacuations, transfers, and labor conditions through what can only be termed selective military assimilation. Correct doctrinal application of the Convention requires careful attention to these provisions both to ensure faithful adherence to the Convention’s hard won bargains but also to prevent repeating the historical failures of military assimilation as a protective regime.

Amendment by Assimilation

More concerning than imprecision with or overstating the extent of military assimilation, however, are resorts to military assimilation to springboard more ambitious revisions to the Third Convention’s treatment regime. The alleged principle of military assimilation has been cited, for instance, to extend human rights law protections applicable to members of the detaining power’s armed forces to prisoners of war. This argument alleges that because prisoners of war are effectively assimilated as soldiers of the detaining power, they, like members of the armed forces, enjoy human rights vis à vis the detaining power.

For example, the ICRC Commentary envisions through military assimilation an incorporation of human rights law to prisoners of war. It observes,

Through the principle of assimilation, developments in international law since 1949, including human rights law, as far as they have been incorporated into the domestic legal system governing military personnel, will become applicable to prisoners of war, for example in terms of the relevant procedures for placement in and release from confinement awaiting trial. (para. 4022).

To the extent the Committee means merely to remark that prisoners of war will coincidentally (and in all likelihood collaterally) benefit from States’ application of international human rights law standards to their armed forces, the observation is not particularly concerning. The human rights assimilation argument may be reasonable as far as military assimilation actually features in the Convention—that is, the extent to which standards applicable to members of the Detaining Power’s armed forces reflect implementation of that State’s human rights obligations.

However, understood in conjunction with the overbroad claim that military assimilation is a pervasive or universal aspect of prisoner of war treatment more generally, human rights incorporation proves too much. That is, if military assimilation is to inform prisoner of war treatment “as a whole,” human rights law standards might be understood to displace the carefully crafted and selective resorts by the Third Convention to assimilation. Worse, unrestrained military assimilation might be understood to undo the considered repeals and amendments made to prisoner of war protection through assimilation. In cases where the Convention abandons assimilation, the extension of human rights obligations would undermine the Convention’s evolved and selective scheme of protection.

To be sure, military assimilation offers potential humanitarian benefits. States have confirmed as much by retaining military assimilation in some aspects of the Third Convention. Military assimilation still offers the potential to improve the lot of prisoners of war as vulnerable victims of armed conflict. First, as has long been noted, military assimilation offers valuable economy to detention operations, permitting a detaining power to resort to supplies, procedures, and protections which it already has on hand and with which it has facility and experience. Second, military assimilation also amounts to a very practical form of differential obligations, inherently matched to the existing resources and capabilities of various States. Last, as the International Committee of the Red Cross and others urge, military assimilation can involve an updating function that is difficult to secure through other means of revision such as treaty amendment. As States improve and modernize the treatment and regulation of their armed forces, prisoners of war enjoy similar improvements and modernizations to the extent military assimilation applies.

But at present, such broad claims respecting military assimilation and human rights law are not accompanied by widespread, nearly universal practice of States. In fact, some detaining powers, confronted with expectations of applying human rights law to wartime detention, have scaled back or even abandoned detention operations, outsourcing them to allied partners who operate free from such restraints. Yet the reach and influence of the advocates of human rights incorporation by military assimilation portends future misunderstandings in this respect.

Concluding Thoughts

Despite its benefits and efficiencies, States have resorted to military assimilation only selectively for good reason. With its ancient roots and wide operational use, military assimilation has not proved a failsafe. In the immediate wake of the two world wars’ mixed and even negative experiences with military assimilation, commentary contemporaneous to the 1949 Third Convention included an important caution. Jean Pictet observed, “The experience of the 1914-1918 war showed, however, that abuses might result from any strict assimilation of prisoners of war with the armed forces of the Detaining Power.” (p. 406)

To be sure, principles are attractive for setting patterns of meaning that enhance general understanding, predictability, and certainty. Principles may in this sense perform some of the interpretive work often assigned to the objects and purposes of treaties. But they should not paper over clear doctrinal choices by States. Nor should they be used effectively to amend the instruments they seek to convey or clarify.

Overall, the picture of military assimilation in the Third Convention is less one of an overarching principle or theme running through the whole of the Convention and more of an occasional technique to secure compromise on historically fraught issues of prisoner of war treatment. Careful study and appreciation of the Convention’s selective and limited resort to military assimilation is essential to a correct understanding of States’ prisoner of war treatment obligations.


Sean Watts is a Professor in the Department of Law at the United States Military Academy, Co-Director of the Lieber Institute for Law and Land Warfare at West Point, and Co-Editor-in-Chief of Articles of War.


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