About the author(s):
Gloria Gaggioli is Full Professor of Public International Law at the University of Geneva. Her research focuses on international humanitarian law and its interplay with international human rights law, with particular expertise in the regulation of the use of force, non-State armed groups, and counter-terrorism. She served as Director of the Geneva Academy of International Humanitarian Law and Human Rights (2020–2024) and as Vice-Dean of the Faculty of Law at the University of Geneva (2024–2026). She has been a member of the Board of Geneva Call since 2019 and previously worked as a Legal Adviser in the Legal Division of the International Committee of the Red Cross (2011–2014). She has also been a visiting professor or researcher at academic institutions in Europe, the United States, and China.
* This blog has been edited with the assistance of ChatGPT.
Conflict classification is one of the most perilous and consequential exercises under international humanitarian law (IHL); and it is probably even more so with respect to non-international armed conflicts (NIACs), which are – as we know – the most prevalent form of armed conflict today.
One of the complicating factors in relation to NIACs is the fact that, under conventional law, two different thresholds of application coexist. They are set forth respectively in Common Article 3 to the four Geneva Conventions (CA3) and in Additional Protocol II (APII). As a result, the IHL community often refers to the so-called dichotomy between “CA3 NIACs” and “APII NIACs”.
Is it still relevant to maintain this duality of NIACs under contemporary international law? This is the central question raised and discussed with mastery and nuance in Chapter One of Nathan Derejko’s book Identifying Non-International Armed Conflict, which proposes what might be described as an internal harmonization of the law governing NIACs.
In this blog post, I explain what I find convincing about Derejko’s arguments in favour of a single definition of NIACs (as opposed to the separation between CA3 NIACs and APII NIACs). I also highlight the limits of his arguments, outlining how and where they could have been taken even further.
1. Complexities and Challenges Related to Bifurcated NIAC Classification
As explained by Derejko, this duality is the result of a complex – and often convoluted – drafting history. Traditionally, for obvious sovereignty reasons, States have been reluctant to develop the law governing NIACs. While CA3 was drafted to apply broadly, APII expanded the substantive rules while limiting its scope to a narrower category of NIACs. Accordingly, APII applies only to a narrowly defined category of NIACs involving a State and an organized armed group operating on its territory.
While CA3 does not define NIACs, the notion has been further elaborated through the jurisprudence of international criminal courts and tribunals. Most notably, the seminal Tadic (§70) case defined NIACs as “protracted armed violence between governmental authorities and organized armed groups or between such groups within a State”.
This definition – which is often understood as a “concise articulation of the material elements of NIAC pursuant to CA3” (Derejko, p. 40) – has been extensively compared with APII, giving rise to divergent interpretations and further fragmentation of the field. This has generated four principal interpretative questions, each thoroughly examined by Derejko :
- Is “responsible command” a specific requirement for APII NIACs or an inherent element of all NIACs?
- Is territorial control by an organized armed group truly indispensable for an APII NIAC?
- Is “protracted armed violence” under Tadic materially different from “sustained and concerted military operations” under APII?
- Is the ability to implement IHL an additional requirement under APII, or is it equally inherent in all NIACs?
2. Derjeko’s Convincing Arguments in Favour of a Singular Definition
Essentially, Derejko argues that, upon closer analysis, the distinctions traditionally drawn between CA3 NIACs – as elaborated in Tadic – and APII NIACs have progressively faded away. His demonstration rests on three principal propositions:
- First, “responsible command” and the ability to implement IHL are not autonomous requirements specific to APII but are inherent in the organization criterion applicable to all NIACs.
- Second, territorial control is merely an enabling factor rather than an independent constitutive requirement. (See also in this sense Sivakumaran, p. 186).
- Third, the notions of “protracted armed violence” under Tadic and “sustained and concerted military operations” under APII do not reflect different thresholds of intensity but are used interchangeably in the jurisprudence.
Collectively, these arguments support the conclusion that the thresholds of organization and intensity are effectively identical under CA3 and APII, thereby warranting a singular definition of NIACs.
I find these arguments persuasive, particularly the proposition that responsible command and the ability to implement IHL are inherent elements of the organization criterion rather than additional requirements. As we have argued elsewhere (Gaggioli & Kilibarda, p. 214), the ratio legis of the organization criterion is precisely that armed groups must be capable of implementing IHL, something that would be impossible without responsible command. The existence of an accountability mechanism allowing the group to respect IHL is thus, in our view, a minimum requirement, not a mere indicative factor. Regarding territorial control, it is worth highlighting Derejko’s innovative argument that territorial control may equally be required for the implementation of certain IHL rules in CA3 NIACs, such as those governing detention or judicial proceedings by organized armed groups. Lastly, the absence of any meaningful difference in the intensity threshold is further illustrated by the fact that armed conflicts between organized armed groups may reach particularly high levels of violence and yet remain governed only by CA3, as APII does not apply to such conflicts.
Additionally, Derejko demonstrates that the harmonization extends beyond the threshold of application. Through the progressive development of treaty and customary law, the substantive rules governing CA3 and APII NIACs have become largely identical. The ICRC Customary IHL Study, which does not distinguish between CA3 and APII NIACs, the amended scope of application of the CCW, which extends its applicability to NIACs without further distinction, and the Rome Statute, which abandoned the APII threshold, all illustrate this trend. Even if a handful of APII provisions remain purely conventional, the normative content of NIACs is largely unified.
As a result, the core finding of Chapter One is that “the Tadic definition of NIAC (…) has effectively harmonized the two conventional NIAC thresholds of CA3 and APII. In addition, the progressive development of conventional and customary IHL has largely, albeit not entirely harmonized the rules applicable to both variants of NIAC. (…).” (Derejko, p. 60).
This is a particularly welcome simplification of the definition of NIACs, one that promises to be influential in both the practice and the teaching of IHL.
Importantly, this unified definition does not erase the diversity of NIACs. Derejko usefully distinguishes between classic, extraterritorial, transnational, multinational and internationalized NIACs, thereby preserving the added value of existing typologies while rejecting the idea of multiple legal thresholds. (See e.g. Vité; ICRC Challenges Report 2011; Kilibarda & Gaggioli, p. 136)
3. Limits of Derejko’s Arguments in Favour of a Singular Definition
One of the greatest strengths of Chapter One is its attempt to simplify the definition of NIAC. Beyond its practical usefulness for conflict classification, this streamlined approach to IHL interpretation is particularly timely. At a moment when IHL is increasingly contested by States and when exceptions tend to receive disproportionate attention, a simpler and more principled understanding of the law may be exactly what is needed. Over the past two decades, IHL has evolved considerably through judicial and scholarly interpretation. These developments have undoubtedly enriched the field, but they have also made it increasingly nuanced, intellectually demanding, and sometimes fragmented. One may therefore wonder whether the time has come to strengthen IHL not by further complexifying it, but by returning to its core content and simplifying its conceptual architecture.
However, this streamlined approach does not run throughout the entire book. It sits somewhat uneasily alongside Chapters 5 (geographical scope of NIAC) and 6 (temporal scope of NIAC), which advocate a functional approach, i.e. an approach that is informed by “complex factual realities” (Derejko, p.11) and that is rule-specific. While this functional approach is both original and sophisticated, it appears necessarily more fragmented than the streamlined approach advocated in Chapter One. It may also prove too flexible and unpredictable, thereby contributing to the complexification of the field. Some readers may therefore perceive a tension between these two approaches, reflecting competing visions of how IHL should be interpreted, applied, and perhaps even progressively developed.
More specifically regarding Chapter One in itself, some may be disappointed that Derejko ultimately maintains that a distinction between CA3 NIACs and APII NIACs continues to exist. Two differences remain that he neither fully resolves nor eliminates.
First, Derejko does not question the interpretation that APII does not apply to armed conflicts between organized armed groups. At some point, Derejko appears to interestingly question whether such conflicts can genuinely exist, relying on the argument that the territorial State is under a human rights obligation to intervene before armed violence reaches the threshold of a NIAC (Derejko, pp. 64–65). Although this argument is only briefly mentioned and is not entirely persuasive at first sight (as it mixes up legal obligations under HRL and the reality which IHL is supposed to address), the point deserved further development. Had it been explored more fully, it might have supported an even closer convergence between CA3 and APII NIACs.
Second, Derejko does not question the interpretation that APII does not apply to extraterritorial NIACs, despite the fact that strong arguments have been advanced in the literature to downplay this territorial limitation on humanitarian, interoperability, and common-sense grounds (See e.g. Bellal, Giacca and Casey-Maslen, p. 60; Clapham, pp. 38-39). Many of these arguments emerged from the experience of the conflict in Afghanistan. It appeared difficult to justify why APII would apply to hostilities between the Afghan government and armed groups such as the Taliban or Al-Qaeda, yet not to hostilities between intervening States and those very same armed groups. While Derejko discusses these challenges, he ultimately does not seize the opportunity to further harmonize CA3 and APII NIACs. Instead, he adheres to a more classical interpretation based on the ordinary meaning of the text of APII.
In short, while Derejko succeeds in clarifying and streamlining the law, he stops short of removing all the remaining barriers to a fully harmonized concept of NIAC. In his view, the Tadic criteria trigger the application of the law of NIAC, whereas APII remains conventionally applicable only to the traditional civil wars, i.e. internal conflicts between a State and an organized armed group. This is a somewhat disappointing conclusion. The remaining obstacles do not appear inherently more difficult to overcome than the territorial control requirement or the responsible command criterion, both of which Derejko convincingly reinterprets. Readers persuaded by his earlier arguments may therefore be left wanting more.
More fundamentally, Derejko’s project invites a broader question: could the logic of harmonization be taken one step further? Rather than limiting the discussion to the relationship between CA3 and APII, should we not also reconsider the broader divide between international and non-international armed conflicts? Or at least facilitate the internationalization of NIACs? Even if the thresholds for their application remain distinct, there may be a compelling case for further harmonizing their substantive rules. This idea was particularly influential more than 20 years ago (see, e.g., James Stewart; Eric David) and could be revisited to provide a natural extension of Derejko’s broader project of internal harmonization within IHL.