Contemporary IHL challenges: Use of force and non-international armed conflicts

The ICRC recently published a new report on the "Use of Force in Armed Conflicts". The outcome of an expert meeting held in Switzerland, the report examines the interplay between the conduct of hostilities and law enforcement paradigms, particularly in non-international armed conflicts (NIACs). We were very fortunate to have a number of American experts from both the government and academic circles participate in the meeting, including Brigadier General Richard Gross (Legal Counsel to the Chairman of the Joint Chiefs of Staff), Richard Jackson (Special Assistant for Law of War Matters, US Army), Professor Robert Chesney (University of Texas School of Law), and Professor Robert Goldman (American University Washington College of Law). In addition, Colonel Kirby Abbott of Canada (Deputy Judge Advocate General, Strategic, Canadian Armed Forces) also took part. The report is of particular interest in that it not only addresses the interplay between international humanitarian law (IHL) and international human rights law (IHRL) from a conceptual perspective, but it also focuses on concrete case studies that reflect real-life situations arising in armed conflicts. In particular, riots, the fight against criminality, escape attempts, and checkpoint management. The ICRC hopes to organize a panel discussion on these issues in 2014. (More to follow on this in the coming weeks.) Until then, click here to download or order a print copy of the report.

Meanwhile, here at Intercross, we wanted to further explore the interplay between IHL and IHRL from a US perspective as part of our broader ongoing "IHL and Contemporary Challenges" series so we invited Charles P. Trumbull to contribute a guest post on the laws applicable to NIACs. Charles is an attorney-adviser at the United States Department of State, Office of the Legal Adviser. He worked in the Office of the Assistant Legal Adviser for Political Military Affairs from 2011-2013, and is currently serving as the Deputy Special Envoy for the Closure of Guantanamo Bay. The views expressed in this post are his own and not necessarily those of the Department of State, the U.S Government, or the ICRC.   


Filling the “Gaps” in the Law Applicable to Non-International Armed Conflicts[1]

By Charles P. Trumbull

It is generally acknowledged that international humanitarian law (IHL) does not provide detailed guidance to States in non-international armed conflicts (NIACS).  The four Geneva Conventions contain only one article, Common Article 3, applicable in NIACs compared to the hundreds of articles that apply in international armed conflicts (IACs).  Additional Protocol II (APII) expands on the protections contained in Common Article 3, but the United States is not a party to the Protocol, and is thus not bound by its provisions except to the extent that they reflect customary international law (CIL).  CIL offers a little more guidance.  The principles of proportionality, distinction, and humanity, for example, would apply equally in IACs and NIACs.  There is often no clear consensus, however, on whether state practice in NIAC has evolved into custom.  For these reasons, the ICRC, among others, has declared that there are “gaps or weaknesses” in the existing legal framework applicable to NIACs.[2]  

This essay focuses on one of the key gaps identified by the ICRC study – protection for persons deprived of their liberty – and discusses the different sources of law that States may look to for guidance in the absence of a clear obligation.  In particular, it explains how States attempt to fill gaps in the legal framework by analogizing to rules applicable in IACs as well as by looking to human rights law (HRL).   

I begin with one comment on terminology.  The term “gaps” suggests that IHL is somehow deficient, like a leaky ship, and that we need to find or create law to fill those gaps.  People are understandably concerned about “law free zones”, and there is thus a natural inclination to think that we need more laws.  This view, however, is in tension with the underlying premise of international law, which is that States are free to act unless there is a rule prohibiting such action.  Similarly, with the exception of peremptory norms, States are generally free to decide what obligations to undertake.  And, States clearly did not intend to undertake as comprehensive a set of obligations with respect to NIACs as they did in the Geneva Conventions applicable to IACs.  The drafters of the Geneva Conventions primarily thought of intra-state civil wars when they referred to NIACs.  States never intended to establish a comprehensive international law framework for such conflicts, which they believed were internal affairs that were properly regulated by domestic (and not international) law. Accordingly, States agreed only to the bare minimum requirements that appear in Common Article 3 and later in APII.

Many NIACs today extend beyond a State’s borders, but are nevertheless governed by the bare bone rules that were initially drafted for civil wars.  People may reasonably disagree on whether this is good or bad, but there may be some utility in allowing the law in NIACs to develop gradually.  As Justice Oliver Wendell Holmes Jr. observed: “The life of law has not been logic; it has been experience.”[3]  Rushing to create new laws deprives the international community from the benefit of the experience that we are developing in this new type of conflict. 

Regardless of whether the “gaps” should be filled by more law, the existing legal framework provides little guidance to States on a number of key issues related to NIACs. The rules governing detention operations are especially sparse.  Common Article 3 and APII both contemplate that States may detain persons during armed conflict without criminal charge or other judicial process.  APII, for example, refers to “persons whose liberty has been restricted for reasons related to the conflict.”  Article 2(2).  Common Article 3 similarly refers to persons placed “hors de combat by sickness, wounds, detention, or any other cause.”  Both Common Article 3 and APII mandate important protections for detainees (e.g., humane treatment, no torture, no summary executions, etc), but they do not provide any clarity on a number of important questions related to detention.  The black letter law does not tell States who can be detained or for how long.  It does not mandate procedures for determining the legality of detention, or establish rules for the repatriation of detainees.  Nor does it offer guidance on minor questions such as the amount of exercise detainees should have each day, which is one of the many issues addressed in the more developed rules for Prisoners of War in IACs. 

States could, as a policy matter, attempt to fill these gaps in a couple ways.  First, we could look to the rules applicable in IAC and assess whether they might apply by analogy to NIACs.  Second, although IHL is the lex specialis in armed conflict, we may look to human rights law under certain circumstances.  

  1. Gap Filling by Analogy

Gap filling by analogy entails examining the rules applicable in IACs and determining whether they can practically be applied in NIACs.  This requires a “translation exercise” since the rules in IACs are sometimes difficult to apply directly in NIACs.  The rules of IACs, for example, generally presume that combatants are members of the State’s armed forces, wear uniforms, and qualify for POW status.  In NIACs, however, non-state belligerents rarely wear uniforms, do not qualify for POW protections, and generally do not have the resources to provide POW protections for those soldiers they detain.  Accordingly, certain IAC rules cannot be applied word for word in NIACs. 

Gap filling might also require us to discern the overall objective or purpose of an IAC rule, even if we do not think it is necessary or appropriate to strictly apply the black letter law from IAC. GCIII, Article 22, for example, requires POWs to be interned only in premises located on land.  This rule was motivated by the concern that, in 1949, ships were not suitable places for detention: they were cramped, dirty, crowded, exposed to enemy fire, etc.  These considerations might not all be relevant in modern NIACs given advancements in technology and the lack of maritime hostilities in most NIACs.  Accordingly, there may be situations in which it would be acceptable to detain an enemy belligerent temporarily on a ship, such as in the case of Ahmed Warsame.  But looking to the spirit of GCIII, Article 22, would limit the situations in which this would be appropriate.  In other words, detention on a ship may be appropriate only if it can be carried out under conditions similar to what would be provided on land. 

Determining the appropriate analogy – and thus which rules to apply – may also generate significant debate.  In the detention context, for example, there is ongoing discussion regarding whether it is more appropriate to apply by analogy the rules from GCIII (which applies to POWs) or the rules of GCIV (related to the internment of civilians). Underlying this debate is the following question: Are members of non-state armed groups more like members of a state’s armed forces or are they more akin to ordinary civilians who decide to pick up arms?

The answer to this question has significant consequences. Under GCIII, members of the enemy forces can be detained based on their status as combatants.  They can also be detained until the end of hostilities. Under GCIV, Article 78, civilians can be interned only if the Occupying Power “considers it necessary, for imperative reasons of security,” and only for so long as they remain a threat.  Furthermore, unlike POWs, their cases must be reviewed by a court or administrative board at least twice a year. (See also GCIII, Article 42).  Thus, States are faced with adopting a status-based criteria or a threat based criteria, or perhaps some combination of both, for individuals detained in NIACs.

The United States has adopted the GCIII analogy, since the underlying rationale for detaining POWs until the end of hostilities also applies to members of armed groups in NIACs.  Like soldiers, they frequently swear an oath of allegiance, operate within a chain of command, are committed to the destruction of the enemy, and may return to the fight if released without proper safeguards.  Thus, as a legal matter, based on the authorities in the 2001 Authorization for Use of Military Force, the United States took the position in habeas litigation starting in March of 2009 that it can detain “persons who are part of, or substantially supported, Taliban or Al-Qaeda or associated forces that are engaged in hostilities against the United States.”  This position was subsequently adopted by the judiciary and the U.S. Congress.

There are some weaknesses in this POW analogy, which is why we need to conduct a translation exercise in applying IAC rules to the NIAC context.  For one, unlike in IACs, there is no clear end to many NIACs, especially those against terrorist organizations like Al-Qaeda.  The indeterminate nature of these conflicts raises significant concerns about prolonged detention.  Second, members of armed groups do not have combatant’s privilege, which protects combatants against prosecution for engaging in hostilities consistent with IHL.  Combatant’s privilege helps to mitigate some of the concerns with administrative detention in IACs.  POWs may have to endure several years of captivity without trial, but they also know that they will be released and repatriated at the end of the war.  Members of armed groups do not have that same assurance, since they can be prosecuted under domestic law for engaging in hostilities.  This may exacerbate the period of administrative detention. 

In light of these concerns, the USG has incorporated, as a matter of policy, some of the safeguards in GCIV that apply to civilian internees.  Detainee Review Board (DRB) procedures in Afghanistan, for example, include a threat assessment. Even if a detainee is determined to meet the legal criteria for detention, the DRB also considers whether continued internment is necessary to mitigate the threat that the detainee poses.  If the detainee no longer poses a threat, or if the detainee’s threat can be appropriately mitigated in his home (or another) country, then the detainee should be released from DoD custody.   DoD also reviews each detainee in U.S. custody at Bagram every six months, consistent with the civilian internment provisions in GCIV.  The Periodic Review Board process for Guantanamo detainees similarly takes detainees’ future threat into account when reviewing whether continued law of war detention is warranted.  These procedures may not be strictly required as a matter of international law, but they are important to facilitating international acceptance and support for our detention operations.  

  1. Gap Filling by Reference to Human Rights Law

Even applying rules of IAC to NIAC, there will still be “gaps” in the legal framework. Accordingly, in appropriate circumstances, States may look to human rights law for guidance.  As a legal matter the relationship between IHL and HRL in situations of armed conflict remains unclear, and States have divergent views on the proper application of HRL during armed conflict.   

  1. IHL as Lex Specialis

It is generally accepted that IHL is the lex specialis in armed conflict.  This is a doctrine of international law which provides that where two different sets of legal rules purport to govern the same factual situation, a law governing a specific subject matter (lex specialis) overrides a law which only governs general matters (lex generalis).  The more specific rule is preferable because it (1) better represents States’ intentions on how to regulate the given situation and (2) was designed to take into account the unique contextual factors.  IHL was specifically intended to apply only situations of armed conflict and is thus considered the lex specialis. 

Before turning to the application of lex specialis, it is important to note that IHL rules do not necessarily result in decreased protections for the individual, especially in IACs.  In many circumstances, the IHL rule will actually be more “humanitarian” than the relevant HRL rule.  For example, ICCPR Article 10 provides that persons deprived of liberty shall be treated with humanity and respect for the inherent dignity of the human person. GCIII-IV, by contrast, contain numerous provisions detailing the treatment that POWs and interned civilians are entitled to.  GCIII, Article 38, for example, requires detaining authorities to “encourage the practice of intellectual, educational, and recreational pursuits, sports and games amongst prisoners and … take the measures necessary to ensure the exercise thereof by providing them with adequate premises and necessary equipment.”  Contrasted with the treatment provisions in the Third and Fourth Geneva Conventions, it is difficult to say it is more feasible, or more advantageous to the individual deprived of liberty, to encourage each State to interpret and apply the more general rule.

Recognizing that IHL is the lex specialis, however, does not provide much clarity on how IHL and HRL interact, and there is no clear consensus on how these two bodies of law apply in situations of armed conflict.  The ICJ had the opportunity to clarify the relationship in the Legal Consequences of the Construction of a Wall case, involving Israel’s construction of a security wall around parts of Palestine. This is how the Court framed its inquiry: 

The Court considers that the protection offered by human rights conventions does not cease in case of armed conflict, save through the effect of provisions for derogation …. As regards the relationship between IHL and HRL, there are thus three possible situations:  some rights may be exclusively matters of international humanitarian law; others may be exclusively matters of human rights law; yet others may be matters of both these branches of international law.  In order to answer the question put to it, the Court will have to take into consideration both these branches of international law, namely human rights law and, as lex specialis, international humanitarian law.[4]

The ICJ did not elaborate on the three possible situations, however, thus leaving States to wrestle with this issue on their own. 

The United States has traditionally taken a narrow view of the applicability of HRL in armed conflict. In its Fourth Periodic Report to the ICCPR in 2011, the USG described its understanding of the relationship between IHL and HRL:

[C]omplex issues arise with respect to the relevant body of law that determines whether a State’s actions in the actual conduct of an armed conflict comport with international law. Under the doctrine of lex specialis, the applicable rules for the protection of individuals and conduct of hostilities in armed conflict are typically found in international humanitarian law, including the Geneva Conventions of 1949, the Hague Regulations of 1907, and other international humanitarian law instruments, as well as in the customary international law of armed conflict. In this context, it is important to bear in mind that international human rights law and the law of armed conflict are in many respects complementary and mutually reinforcing. These two bodies of law contain many similar protections. For example prohibitions on torture and cruel treatment exist in both, and the drafters in each area have drawn from the other in developing aspects of new instruments; the Commentaries to Additional Protocol II to the Geneva Conventions make clear that a number of provisions in the Protocol were modeled on comparable provisions in the ICCPR. Determining the international law rule that applies to a particular action taken by a government in the context of an armed conflict is a fact-specific determination, which cannot be easily generalized, and raises especially complex issues in the context of non-international armed conflicts occurring within a State’s own territory.[5]

The United States did not clarify how it would make such a “fact specific determination.”  Academics, practitioners, and judges have proposed a number of different approaches that the United States could draw from.  While I do not purport to provide a comprehensive review of these theories, I will briefly describe four basic approaches.  

  1. Determining the Relationship Between IHL and HRL

The first approach is the “displacement” model.  This is the most expansive interpretation of IHL as lex specialis and the easiest to apply. Under this theory, IHL “occupies the field” and displaces HRL.  Accordingly, States’ obligations in armed conflict are found exclusively in IHL.

Proponents of this theory argue that countries developed HRL and IHL to address two fundamentally different situations.  HRL was originally developed to protect citizens from their own government, while IHL regulated wartime relations between States and enemy combatants and foreign civilians. This school of thought also points to the fact that certain protections guaranteed by the Additional Protocols to the Geneva Conventions overlap with protections provided in the ICCPR.  It would not have been necessary to include these provisions in the Additional Protocols – which were negotiated after the ICCPR - if States understood that these HRL obligations would continue to apply in armed conflict.[6]

Even under this theory, however, lex specialis would not preclude HRL’s application to conduct unrelated to or outside of the armed conflict.  A government would still be required to provide HRL due process protections, for example, to a citizen accused of committing a common crime.

The second approach is the “rule conflict” model.  IHL trumps HRL only where there is a conflict or inconsistency between two potentially applicable rules.  This theory, which requires a provision-by-provision or issue-by-issue analysis, recognizes that it many cases IHL and HRL are compatible and mutually reinforcing.  Both frameworks, for example, prohibit torture.  Thus, pursuant to this theory, both Article 7 of the ICCPR and Common Article 3 to the Geneva Conventions would continue to apply in NIACs since they do not pose inconsistent obligations. 

Consider the following example of a direct conflict.  The Fourth Geneva Convention permits security detention based on administrative review.  See GCIV, Article 5.  HRL also permits security detention in some circumstances, but requires judicial review.  See ICCPR, Article 9.  In this context, the rule governing the more specific subject matter, the IHL rule, would prevail.  Another example of a slight inconsistency could be the right under the ICCPR Article 17 to not have arbitrary interference with privacy, family, home or correspondence.  Article 76 of GCIII, on the other hand, specifically permits censorship of POW correspondence.   

A conflict might also arise if IHL is silent on an issue for which HRL creates a safeguard.  The lacuna in IHL may indicate States’ belief that certain safeguards should not be applicable in armed conflict. Article 9(2) of ICCPR, for example says that anyone who is arrested shall be informed at the time of arrest of the reasons for his arrest and shall promptly be informed of any charges against him.  Nothing in the Geneva Conventions imposes a similar obligation with respect to battlefield detentions. 

The third approach is the “interpretive” model.  According to this theory, both HRL and IHL apply in an armed conflict, but HRL must be interpreted in light of the lex specialis rules of IHL.  In other words, IHL acts as the lens through which HRL obligations must be viewed. 

The International Court of Justice seemingly adopted this approach in the Advisory Opinion on the Legality of the Threat or Use of Nuclear Weapons. This case arose after the General Assembly asked the ICJ whether “the threat or use of nuclear weapons in any circumstances [is] permitted under international law.”[7]  A number of countries appearing before the Court argued that the use of nuclear weapons would violate the right to life as guaranteed in Article 6 of the ICCPR.  Other countries argued that “the Covenant was directed to the protection of human rights in peacetime, but that questions relating to unlawful loss of life in hostilities were governed by the law applicable in armed conflict.”[8]  The Court attempted to reconcile these contrasting positions as follows:

In principle, the right not arbitrarily to be deprived of one’s life applies also in hostilities.  The test of what is an arbitrary deprivation of life, however, then falls to be determined by the applicable lex specialis, namely the law applicable in armed conflict which is designed to regulate the conduct of hostilities.  Thus whether a particular loss of life through the use of a certain weapon in warfare is to be considered an arbitrary deprivation of life contrary to Article 6 of the ICCPR, can only be decided by reference to the law applicable in armed conflict and not deduced from the terms of the ICCPR itself.[9]

In other words, HRL applies in form but its specific content is determined by IHL, at least where there are overlapping or complimentary obligations. 

This approach might appear to render HRL irrelevant during armed conflict.  The fact that HRL would continue to apply in form, however, has significant implications for States and individuals.  Unlike in IHL, many human rights treaties establish a right to an individual remedy.  Article 2(3)(a) of the ICCPR, for example, obliges State Parties “[t]o ensure that any person whose rights or freedoms as herein recognized are violated shall have an effective remedy, notwithstanding that the violation has been committed by persons acting in an official capacity.”  This right is generally interpreted to include civil redress.  Accordingly, under this theory, victims of IHL violations may have a right to seek redress, since certain IHL violations will ipso jure violate a corresponding obligation under HRL. 

The interpretive approach is best suited for those HRL rules that have qualifiers like “unlawful” or “arbitrary”.  In these cases, the meaning of “arbitrary” can be settled by reference to IHL.  This approach does not solve cases of direct conflict - for example, the right of a detained person under the ICCPR to challenge before a court the issue of lawfulness of detention contrasted with IHL, which provides for certain administrative reviews but not court review.  Compare ICCPR, Article 9(4) with GCIII, Article 21 and GCIV, Article 78.

Fourth, is the “kitchen sink” model.  IHL and HRL are complementary and both apply in their entirety in situations of armed conflict, at least in certain circumstances. 

This may have been the European Court of Human Rights’s (ECtHR) theory in its July 2011 decision in al Skeini v. United Kingdom.  This case was brought by the family members of six Iraqi civilians who were killed by British forces in Basrah in 2003.  The family members argued that the UK had failed to conduct adequate investigations into these deaths, resulting in a violation of Article 2 of the European Convention on Human Rights (ECHR), which protects against arbitrary deprivation of life.  The UK conceded that the ECHR would apply to British forces on British military bases, but argued that it was not applicable outside of these bases.  The Court rejected the UK’s jurisdictional argument, holding that “the United Kingdom, through its soldiers engaged in security operations in Basrah during the period in question, exercised authority and control over individuals killed in the course of such security operations, so as to establish a jurisdictional link between the deceased and the United Kingdom for the purposes of Article 1 of the Convention.”[10]  After resolving the jurisdictional question, the Court unanimously found that the UK had violated its obligations under Article 2. Significantly, the Court did not consider the applicable IHL obligations, or indicate that the HRL obligations should be interpreted differently during armed conflict in light of the lex specialis, IHL.  

  1. Practical Considerations

In practice, none of the four approaches described above is viable on its own.  There is no single model for determining the proper relationship between HRL and IHL in armed conflict.  The applicability of certain HRL obligations, and the proper interpretation of those obligations, depends on several considerations. 

First, the territorial scope of the particular human rights treaty is relevant.  Some treaties, or some provisions, by their terms do not apply extra-territorially.  Accordingly, they might apply in intra-state conflicts like civil wars, but not in transnational NIACs like the one between the United States and Al-Qaeda.  The ICCPR, for example, provides that “Each Party to the present Convention undertakes to respect and to ensure to all individuals within its territory AND subject to its jurisdiction the rights recognized in the present Covenant.”  Article 2(1).  The United States has historically interpreted these two clauses as conjunctive: the ICCPR applies only when both criteria are satisfied.  Other countries, however, argue that it must be interpreted as disjunctive, so that it applies to individuals within its territory OR subject to its jurisdiction. 

Second, the location of the conflict is relevant. There is no question about extraterritorial application of human rights obligations within a State’s own territory.  There is also a stronger argument that human rights continue to apply in internal armed conflicts, since the original objective of HRL was to protect citizens from their own governments.

Third, some human rights treaties permit States to derogate from certain obligations during emergency situations.  ICCPR Article 4(1), for example, permits States to take measures derogating from specific obligations under the Convention in “time of public emergency which threatens the life of the nation and the existence of which is officially proclaimed.”  Accordingly, even if we determine that HRL might apply in principle, certain rules would not apply following an official derogation.

Fourth, the characterization of the conflict will likely affect the lex specialis determination.  The argument that IHL occupies the field is significantly stronger in IACs, where the treaty rules are comprehensive and often more detailed than corresponding HRL obligations.  The specificity in the legal framework applicable in IACs lends greater support to the argument that States intended these rules (rather than HRL) to apply in such situations. 

Finally, it is often helpful to dive a little deeper and examine the actual rules and whether HRL rules are amenable to reasonable application in armed conflict.  Too often, the debate gets wrapped up in the meta questions of whether HRL applies or how HRL and IHL interact.  States are not likely to come to any general agreement on these abstract questions. But, if we look at specific rules, we can narrow down the differences.  Many human rights obligations simply are not relevant to military operations (such as the right to participate in elections) or may only be relevant to certain aspect of military operations, such as detentions.  In other cases, IHL and HRL impose the same obligation, as with the prohibition on torture.  There are only a handful of rules in which there is some real tension.  For some of these it might make sense to apply the rule conflict mode, while for others the interpretive model would be more appropriate. 



[1] The author is an attorney-adviser at the United States Department of State, Office of the Legal Adviser.  He worked in the Office of the Assistant Legal Adviser for Political Military Affairs from 2011-2013, and is currently serving as the Deputy Special Envoy for the Closure of Guantanamo Bay.  The views expressed in this essay are the author’s own views and not necessarily those of the Department of State or the U.S Government.  

[2] Jakob Kellenberger, Official Statement of ICRC: Sixty Years of the Geneva Conventions: Learning from the Past to Better Face the Future (Aug. 12, 2009). 

[3] Oliver Wendell Holmes Jr., The Common Law 1 (1881). 

[4] Legal Consequences of the Construction of a Wall in the Occupied Palestinian Territory, Advisory Opinion, I.C.J. Reports 2004, p. 178. 

[5] Fourth Periodic Report of the United States of America to the United Nations Committee on Human Rights Concerning the International Covenant on Civil and Political Rights, para. 507, available at

[6] But see Article 75(8) (“No provision of this Article may be construed as limiting or infringing any other more favourable provision granting greater protection, under any applicable rules of international law, to persons covered by paragraph 1”). 

[7] Legality of the Threat or Use of Nuclear Weapons, Advisory Opinion, I.C.J Reports 1996, p. 238.

[8] Id. at p. 239. 

[9] Id. at p. 240. 

[10] Case of Al-Skeini and Others v. United Kingdom, European Court of Human Rights, Judgment, para. 149 (July 7, 2011).