The traditional answer of the humanitarian law of international armed conflicts

In international armed conflicts, members of armed forces belonging to a party to the conflict are qualified as ‘combatants’. Combatants may be attacked at any time until they surrender or are otherwise hors de combat, and not only while actually threatening the enemy. Combatants are part of the military potential of the enemy and it is therefore always lawful to attack them for the purpose of weakening that potential. The traditional understanding is that no rule restricts the use of force against combatants only to those circumstances in which they cannot be captured. Within humanitarian law this view has been challenged, citing both the principle of military necessity as a restriction on all violenceFootnote ²⁶ and the prohibition of treacherous killings.Footnote ²⁷ However, neither of these views has been translated into actual battlefield instructions, even less into actual battlefield behaviour.Footnote ²⁸

As for the proportionality requirement, it applies to attacks directed at legitimate targets, but only to protect civilians from their possible incidental effects.Footnote ²⁹ Attacks against combatants are not subject to a proportionality evaluation of the harm inflicted on the combatant and the military advantage derived from the attack.

The unclear answer of the treaty rules of humanitarian law applicable to non-international armed conflicts

In contradistinction to international armed conflicts, it is not clear under the treaty law of non-international armed conflicts when an enemy fighter may be killed (we use the term ‘fighter’ in this article for a member of an armed group with a fighting function and for members of government armed forces). Neither Article 3 common to the Geneva Conventions nor their Protocol II refers to ‘combatants’, because states did not wish to confer the right to participate in hostilities and its corresponding combatant immunity on anyone in non-international armed conflicts. The relevant provisions prohibit ‘violence to life and person, in particular murder’ directed against ‘persons taking no active part in hostilities’, including those who have ceased to take part in hostilities.Footnote ³⁰ Specifically addressing the conduct of hostilities, Article 13 of Protocol II prohibits attacks against civilians ‘unless and for such time as they take a direct part in hostilities’.Footnote ³¹

It may be deduced from these rules and from the absence of any mention of ‘combatants’ that in a non-international armed conflict everyone is a civilian, and that no one may be attacked unless he or she directly participates in hostilities. However, the ICRC Commentary on Protocol II states that ‘[t]hose belonging to armed forces or armed groups may be attacked at any time.’Footnote ³² Otherwise it would, first of all, indeed be astonishing that Article 13 uses the term ‘civilian’ instead of a broader term such as ‘person’.Footnote ³³ Second, if everyone is a civilian, the fundamental principle of distinction becomes meaningless and impossible to apply.Footnote ³⁴ Third, Common Article 3 confers its protection on ‘[p]ersons taking no active part in hostilities, including members of armed forces who have laid down their arms and those [otherwise] placed hors de combat’. The latter phrase suggests that the mere fact of no longer taking active part in hostilities is not enough per se for such members of armed forcesFootnote ³⁵ to be immune from attack: they must take additional steps and actively disengage. Fourth, on a more practical level, to prohibit attacks by government forces on clearly identified fighters unless engaged by those fighters is militarily unrealistic, as it would oblige the government forces to act purely reactively while facilitating hit-and-run operations by the rebel group. The objection that such rebels may be arrested anyway (and their resistance, if any, to arrest would be direct participation in hostilities) is convincing only if the rebels do not control territory.

There are two ways to conceptualize the conclusion that fighters may be attacked at any time until they disengage from the armed group. First, ‘direct participation in hostilities’ can be understood as encompassing the mere fact of remaining a member of the groupFootnote ³⁶ or of retaining a fighting function.Footnote ³⁷ Second, fighters can be considered not to be ‘civilians’ (who are entitled to protection against attacks unless and for such time as they directly participate in hostilities).Footnote ³⁸ However, both interpretations raise difficult questions in practice. How are government forces to determine membership of an armed group so long as the individual in question commits no hostile acts? How can membership of the armed group be distinguished from simple affiliation with a party to conflict for which the group is fighting – in other words, membership in the political, educational or humanitarian wing of a rebel movement? One of the most convincing avenues envisaged is to allow attacks only against a person who either actually directly participates in hostilities or has a function within the armed groups to commit acts that constitute direct participation in the hostilities.Footnote ³⁹

Customary humanitarian law provides no answer

According to the ICRC Study, in both international and non-international armed conflicts ‘[a]ttacks may only be directed against combatants’,Footnote ⁴⁰ while ‘civilians are protected against attack unless and for such time as they take a direct part in hostilities’.Footnote ⁴¹ ‘Civilians are persons who are not members of the armed forces.’Footnote ⁴² The commentary clarifies, however, that the term ‘combatant’ in non-international armed conflicts simply ‘indicat[es] persons who do not enjoy the protection against attacks accorded to civilians’.Footnote ⁴³ ‘While State armed forces may be considered combatants … practice is not clear as to the situation of members of armed opposition groups’.Footnote ⁴⁴ Furthermore, the authors add, ‘[p]ractice is ambiguous as to whether members of armed opposition groups are considered members of armed forces or civilians’.Footnote ⁴⁵ If they are the latter, an imbalance between such groups and government armed forces could be avoided by considering them to take a direct part in hostilities continuously.Footnote ⁴⁶ Customary law is therefore as ambiguous as the treaty provisions on the crucial question of whether fighters in non-international armed conflicts may be attacked in the same way as combatants in international armed conflicts.

Arguments for and against an analogous application of the rule applicable in international armed conflicts

As mentioned above, the general tendency is to bring the law of non-international armed conflicts closer to that of international armed conflicts; this also has the positive side effect that controversies on whether a given conflict is international or non-international, and on what law to apply in conflicts of a mixed nature, are rendered moot. Even those who remain sceptical as to whether state practice has truly eliminated the difference to the extent claimed in the ICRC Study suggest that questions not answered by the law of non-international armed conflicts must be dealt with by analogy to the law of international armed conflicts, except in cases where the very nature of non-international armed conflicts does not allow for such an analogy (e.g. concerning combatant immunity from prosecution and the concept of occupied territories).Footnote ⁴⁷ There is, moreover, no real difference between a non-international armed conflict such as the fighting between Sri Lankan government forces and the LTTE in northern Sri Lanka in 2008 and the international armed conflict between Eritrea and Ethiopia. To require soldiers in non-international (but not in international) conflicts to capture enemies whenever feasible rather than kill them is unrealistic on the battlefield. In addition, the decision when an enemy may be shot at must be taken in a split second by every soldier on the ground, and cannot be left to commanders and courts (as can the decision, discussed later, to intern a person). Clear instructions must exist. Whenever possible, the training of soldiers must be the same for both international and non-international armed conflicts in order to create reflexes that work in the stress of battle.

On the other hand, strong arguments question the appropriateness of applying the same rules as in international armed conflicts. Many non-international armed conflicts are fought against or between groups that are not well structured. It is much more difficult to determine who belongs to an armed group than who belongs to government armed forces. The positive humanitarian law of non-international armed conflicts does not even explicitly prescribe, as does the law of international armed conflicts, that fighters must distinguish themselves from the civilian population. Individuals join and quit armed groups in an informal way, whereas members of government armed forces are formally incorporated and formally dismissed. As armed groups are inevitably illegal, they will do their best not to be recognized as such and to conceal their militant nature. Claiming that fighters may be shot at on sight may therefore put many civilians in danger,Footnote ⁴⁸ whether they are sympathizers of the group, members of the ‘political wing’, belong to the same ethnic group or simply happen to be in the wrong place at the wrong time. And while a clear distinction exists, in international armed conflicts, between the conduct of hostilities by combatants against combatants and law enforcement vis-à-vis civilians by the police, there is no equivalent clear distinction in non-international armed conflicts. Indeed, in a non-international armed conflict, insurgence always constitutes a crime under domestic law. Criminals should be dealt with by courts and may not be ‘punished’ by instant extrajudicial execution.

The arguments in favour of a different rule for non-international armed conflicts obviously apply mainly to armed groups and could therefore be seen as requiring a distinction between government forces and armed groups rather than between international and non-international armed conflicts. The problem is that to have the slightest chance of being respected, humanitarian law must be the same for both sides. The principle of the equality of the belligerents before humanitarian law also applies in non-international armed conflicts.Footnote ⁴⁹

Rules on the peacetime use of force under human rights law

Human rights treaties prohibit the arbitrary deprivation of life. Most instruments, however, do not specify when a killing is arbitrary. Only the European Convention on Human Rights specifies that the deprivation of life will not be deemed arbitrary when it results from the use of force ‘absolutely necessary:

1. (a) in defence of any person from unlawful violence;

2. (b) in order to effect a lawful arrest or to prevent the escape of a person lawfully detained;

3. (c) in action lawfully taken for the purpose of quelling a riot or insurrection’.Footnote ⁵⁰

In its case law outside armed conflicts, the European Court of Human Rights has admitted the lawfulness of killing a person the authorities genuinely thought was about to detonate a bomb, but found that the insufficient planning of the operation violated the right to life.Footnote ⁵¹ With regard to arrest, the Court has found that the life of a fugitive may not be put at risk for the purpose of arresting him if he poses no threat to life and is not suspected of a violent offence, even if he cannot be arrested otherwise.Footnote ⁵²

By and large, other universal and regional human rights bodies take the same approach.Footnote ⁵³ The UN Basic Principles on the Use of Force and Firearms by Law Enforcement Officials provide an authoritative interpretation of the principles that authorities must respect when using force, so as not to infringe the right to life. Those principles limit the use of firearms to cases of

The intentional lethal use of firearms is only admissible ‘when strictly unavoidable in order to protect life’. In addition, law enforcement officials

It must, however, be stressed that the Basic Principles are addressed to officers ‘who exercise police powers, especially the powers of arrest or detention’. Military authorities are included, but only if they exercise police powers,Footnote ⁵⁵ which could be interpreted as meaning e contrario that the rules are not binding for military authorities engaged in the conduct of hostilities. If human rights are to provide an answer as to when a fighter may be killed, it would thus be imperative to know when military authorities, in a situation of armed conflict, are or should be exercising police powers.

The few precedents of human rights bodies in armed conflicts

Theoretically, human rights are the same in international and non-international armed conflicts and outside armed conflicts. The right to life is furthermore not subject to derogations except, under the European Convention, in respect of ‘lawful acts of war’.Footnote ⁵⁶ The classic instance in which a human rights body has assessed the right to life in the context of an armed conflict is the Tablada case, concerning a group of fighters who attacked an army base in Argentina. The Inter-American Commission on Human Rights held that ‘civilians … who attacked the Tablada base … whether singly or as a member of a group thereby … are subject to direct individualized attack to the same extent as combatants’ and lose the benefit of the proportionality principle and of precautionary measures.Footnote ⁵⁷ It then exclusively applied humanitarian law (applicable to international armed conflicts) to those attackers. Only civilian bystanders and attackers who surrendered were considered to be entitled to benefit from the right to life. The Commission did not raise the issue whether the fighters should have been arrested whenever possible, rather than killed.

In the Guerrero case, the Human Rights Committee found Colombia to have arbitrarily deprived persons of their right to life who were suspected – but not proved, even by the subsequent inquiry – to be kidnappers and members of a ‘guerrilla organization’. The police waited for the suspected kidnappers in the house where they had believed the victim of a kidnapping to be held, but which they found empty. When the suspected kidnappers arrived, they were shot without warning, without being given an opportunity to surrender and despite the fact that none of the kidnappers had fired a shot, but simply tried to flee.Footnote ⁵⁸

A national human rights body, the Nepali Human Rights Commission, deemed that the Nepali security forces had seriously violated ‘humanitarian law’ when they shot at a group of armed Maoists forcing students and teachers at a local school to follow a ‘cultural programme’. Six Maoists and four students were killed and five students were injured. The Commission stressed that there was no firing by the Maoists when the army encircled them and that the Maoists were only lightly armed. In the Commission's view, after giving them a warning the army could easily have arrested them. It is not clear whether the Commission found a violation only because of the killed and injured students, or whether it considered that shooting at the armed Maoists without an attempt to arrest them also constituted a violation of ‘humanitarian law’.Footnote ⁵⁹

The jurisprudence of the European Court of Human Rights in cases involving the right to life in the non-international armed conflict in Chechnya includes statements which appear to require that in the planning and execution even of a lawful action against fighters, any risk to life and the use of lethal force must be minimized.Footnote ⁶⁰ While these statements were not limited to protection of the lives of civilians, the actual victims in the case were civilians. In all other cases in which human rights bodies and the ICJ applied the right to life to armed conflicts not of an international character, the persons killed were either hors de combat or not alleged to have been fighters.Footnote ⁶¹ Although fighters are very often killed, for example bombed, while they are not hors de combat, no such case has been brought before an international human rights monitoring body. Some observers have deduced from the absence of any such case law that such killings do not violate the right to life, it being ‘unthinkable’ that a case would be brought before the Inter-American system by a surviving relative of an FARC member.Footnote ⁶²

The limited body of case law thus gives no conclusive answer as to what human rights law requires of government authorities using force against fighters.

Possible solutions under the lex specialis principle

First, we would like to emphasize that there is a good deal of common ground between the two branches of law. In a ‘battlefield-like’ situation, arrest is virtually always impossible without exposing the government forces to disproportionate danger. A fighter presents a great threat to life, even if that threat consists of attacks against armed forces. The immediacy of that threat might be based not only on what the targeted fighter is expected to do, but also on his or her previous behaviour.Footnote ⁶³ In such situations lethal force could therefore be used, even under human rights law. On the other hand, the life of a fighter who is hors de combat is equally protected by both branches.

It is where the solutions found in the two branches actually contradict each other that the need to determine the applicable rule by reference to the lex specialis principle arises. The quintessential example of such a contradiction is that of a guerrilla leader shopping in a supermarket in the government-controlled capital of the country. Many interpret humanitarian law as permitting authorities to shoot to kill, since he is a fighter, but this is controversial. Human rights law would clearly say that he must be arrested and a graduated use of force must be employed, but this conclusion is based on precedents which arose in peacetime and human rights are always more flexible according to the situation.

In our view, some situations are more characteristic of those for which the humanitarian law rule was established, and others are characterized more by facts for which human rights were typically established. There is a sliding scaleFootnote ⁶⁴ between the lone FARC member in a supermarket in Bogotá and the soldier in Franco's forces during the Battle of the Ebro. It is impossible and unnecessary to provide a ‘one size fits all’ answer; as shown above, the lex specialis principle does not determine priorities between two rules in the abstract, but offers a solution to a concrete case in which competing rules lead to different results. The famous ICJ dictum that ‘[t]he test of what constitutes an arbitrary deprivation of life … must be determined by the applicable lex specialis, namely the law applicable in armed conflicts’Footnote ⁶⁵ should not be misunderstood. It has to be read in the context of the opinionFootnote ⁶⁶ in which the ICJ had to determine the legality in abstracto of the use of a certain weapon.

Such a flexible solution, in which the actual behaviour required depends upon the situation, is dangerous – especially in our context, where it has to be applied by every soldier and leads to irreversible results. It is therefore indispensable to determine factors which give precedence either to the rule derived from the humanitarian law of international armed conflicts or to human rights.

The existence and extent of government control over the placeFootnote ⁶⁷ where the killing occurs points to human rights as the lex specialis.Footnote ⁶⁸ For government forces acting on their own territory, control over the place where the attack takes place is not a requirement for human rights to apply,Footnote ⁶⁹ but simply a factor causing human rights to prevail over humanitarian law. The latter was designed to regulate hostilities against forces on or beyond the front line – that is, in a place not under the control of those who attack them, whereas law enforcement concerns persons under the jurisdiction of the enforcers. In traditional conflict situations the question here would be how far away the situation is from the battlefield,Footnote ⁷⁰ although fewer and fewer contemporary conflicts are characterized by front lines and battlefields. What, then, constitutes sufficient control to warrant human rights predominating as the lex specialis? A government cannot simply argue that the presence of a solitary rebel or even a group of rebels on a stable part of its territory indicates that in fact it is not fully in control of the place, and therefore act under humanitarian law as lex specialis. The question is rather one of degree. If a government could effect an arrest (of individuals or groups) without being overly concerned about interference by other rebels in that operation, then it has sufficient control over the place to make human rights prevail as lex specialis.

This criterion of government control leaves the solution slightly more open in an area within the territory of the state whose government is fighting the rebels,Footnote ⁷¹ but which is neither under firm rebel nor under firm government control (such as regions of central Peru at the time of the Sendero Luminoso insurgency).Footnote ⁷² Even where the strict requirements of necessity under human rights law are not fulfilled (if they are, both branches of law lead to the same result), the impossibility of arresting the fighter,Footnote ⁷³ the danger inherent in an attempt to do so,Footnote ⁷⁴ the danger the fighter represents for government forces and civilians and the immediacy of this dangerFootnote ⁷⁵ may cause the conclusion to be reached that humanitarian law is the lex specialis in that situation. These factors are interlinked with the elements of control described above. In addition, where neither party has clear geographical control, the higher the degree of certainty that the target is actually a fighter, the easier it is in our view for the humanitarian law approach to be regarded as lex specialis.Footnote ⁷⁶ Attacks are lawful against persons who are actually fighters, while law enforcement is by definition directed against suspects.

Even where human rights prevail as the lex specialis in the context of armed conflict, humanitarian law remains present in the background and relaxes the human rights requirements of proportionality and warning once an attempt to arrest has been made unsuccessfully or is not feasible. By the same token, where humanitarian law prevails, human rights likewise remain present and require that an inquiry be conducted whenever a person has been deliberately killed.Footnote ⁷⁷

If such a flexible approach to determining the lex specialis is accepted, the question arises whether it is valid for members of both armed groups and government forces. The applicable humanitarian law stipulates the equality of both parties, but they are not equal in terms of human rights obligations.Footnote ⁷⁸ Indeed, it is controversial whether the latter apply to non-state actors.Footnote ⁷⁹ Even if they are, they can only require from them certain conduct towards persons in an area under their control, since such actors have no jurisdiction over a territory.Footnote ⁸⁰ In practice, government soldiers do not shop in supermarkets in rebel-controlled areas. Moreover, a government has the alternative of law enforcement and of applying domestic criminal law and is therefore able to plan an operation that maximizes the possibility of arresting persons.Footnote ⁸¹ Conversely, the question whether armed groups may enforce government legislation or legislate to make government action illegal is controversial. Requiring rebels to detain rather than kill could in some respects increase the asymmetry of conflicts, since detention by rebels is often seen as ‘hostage taking’ and demands are frequently made of them to release government forces they have captured.

It is therefore not unreasonable to consider armed groups as bound only by humanitarian law and domestic law (which in any case renders any killing by them unlawful), whereas government forces are bound by both humanitarian law and human rights, the latter prevailing in some situations and to a certain extent as lex specialis. The fact that rebels do not have human rights obligations limiting attacks on security forces does not mean that there are no humanitarian law limits on such attacks. While police forces cannot be considered to be civilians (as in international armed conflicts) if engaged in law enforcement operations to search for and arrest rebels,Footnote ⁸² attacks on police units not involved in a non-international armed conflict but performing normal peacetime police activities would violate the prohibition on attacking civilians.Footnote ⁸³

The main problem with our solution is whether it is practicable in actual armed conflicts. If the permissible conduct varies, depending on the specific situation, how can a soldier know which rules to apply? This problem can be solved only by precise instructions and rules of engagement for each and every operation and sortie. In addition, guidelines might be developed at international level in discussions between humanitarian law experts, human rights experts, law enforcement practitioners and military representatives. Logically, (former) fighters should also be involved – especially if the guidelines also cover the conduct of such groups – to ensure that they can be applied in practice.

The traditional answer of humanitarian law applicable to international armed conflict

Treaty-based humanitarian law applicable to international armed conflict provides rules procedurally regulating internment. The Third Geneva Convention permits the detaining power to ‘subject prisoners of war to internment’,Footnote ⁸⁵ and the Fourth Geneva Convention allows for internment of a person ‘if the security of the Detaining Power makes it absolutely necessary’Footnote ⁸⁶ or ‘for imperative reasons of security’.Footnote ⁸⁷

Having stipulated when internment may occur, humanitarian law also indicates when it must cease. Some prisoners of war must be repatriated during armed conflict for medical reasons,Footnote ⁸⁸ and all must be released and repatriated, without delay, after the cessation of active hostilities.Footnote ⁸⁹ A civilian must be released ‘as soon as the reasons which necessitated his internment no longer exist’.Footnote ⁹⁰ For those civilians not released during the armed conflict, it states that their ‘[i]nternment shall cease as soon as possible after the close of hostilities’.Footnote ⁹¹

Treaty-based humanitarian law applicable to international armed conflict recognizes that in the case of civilians, who, unlike prisoners of war, cannot be automatically interned for the duration of an armed conflict, compliance with the legal basis for internment requires an assessment to determine whether an individual continues to pose a threat to security and may remain interned, or no longer poses a threat and must be released. Accordingly the Fourth Convention lays down procedures for reviewing the internment of civilians, whether they are aliens in the territory of a party to the conflict or interned in occupied territory, designating the type of review body – either a court or administrative board – and providing for appeal and periodic review.Footnote ⁹² Protocol I introduces an additional safeguard into the process: the person interned is to ‘be informed promptly, in a language he understands, of the reasons why these measures were taken’.Footnote ⁹³ Finally, it should be noted that unlawful confinement is a grave breach of the Fourth Convention.Footnote ⁹⁴

The uncertain answer of treaty-based humanitarian law applicable to non-international armed conflict

In non-international armed conflict, treaty-based humanitarian law prescribes how persons deprived of their liberty for reasons related to the armed conflict must be treated, and lays down judicial guarantees for those undergoing prosecution for offences also related thereto, but it does not clarify for which reasons and by which procedures a person may be interned. Yet the drafters of Protocol II recognized the possibility of internment in non-international armed conflicts, as shown by the specific reference to internment in Articles 5 and 6 thereof.Footnote ⁹⁵

Customary humanitarian law

Customary humanitarian law prohibits the arbitrary deprivation of liberty in both international and non-international armed conflicts.Footnote ⁹⁶ But how is this prohibition to be understood with regard to internment in non-international armed conflicts – that is, what is the basis for it and with which procedures must there be compliance so that such internment does not amount to arbitrary deprivation of liberty? The non-binding commentaryFootnote ⁹⁷ in the ICRC Study interprets this rule by significant reference to human rights. Applying the two criteria of the principle of legality, it states that the basis for internment must be previously established by law and stipulates two procedural requirements: (i) an ‘obligation to inform a person who is arrested of the reasons for arrest’; and (ii) an ‘obligation to provide a person deprived of liberty with an opportunity to challenge the lawfulness of detention’, described as the ‘so-called writ of habeas corpus’.Footnote ⁹⁸

Human rights rules on the procedural regulation of security detention

Human rights provisions regulating the deprivation of liberty can be found in a variety of different treaties. Treaty-based human rights stipulate that a person may be deprived of liberty only ‘on such grounds and in accordance with such procedure as are established by law’.Footnote ⁹⁹ All treaties prohibit arbitrary arrest or detention,Footnote ¹⁰⁰ but only the European Convention specifically lists the bases for depriving a person of his or her liberty.Footnote ¹⁰¹ Treaty-based law articulates two procedures with which compliance is obligatory for a person to be lawfully deprived of his or her liberty when not specifically charged with a crime. First, an arrested person must be promptly informed of the reasons for arrest.Footnote ¹⁰² Second, any person deprived of liberty ‘shall be entitled to take proceedings before a court, in order that that court may decide without delay on the lawfulness of his detention and order his release if the detention is not lawful’.Footnote ¹⁰³

Unlike the four Geneva Conventions, however, none of these treaties is universally ratified, most are regional instruments, and in certain circumstances derogations from the provisions relevant to security detention are possible.Footnote ¹⁰⁴ It would therefore be helpful to have an assessment of the status of universally applicable customary human rights, as well as whether and to what extent such rules are derogable. The same applies to the judicial review requirement, the so-called writ of habeas corpus, because even though it or at least some of its aspects are widely claimed, by among others the Human Rights Committee, to be non-derogable, this is not stipulated in treaty-based human rights law.Footnote ¹⁰⁵

The few precedents of human rights bodies in armed conflicts

Human rights bodies have elaborated upon the content of human rights through their jurisprudence, which does not exist to the same extent for humanitarian law as there are fewer expert bodies mandated to apply it.Footnote ¹⁰⁶ Thus recourse to human rights is appealing when interpreting humanitarian law, but it must be borne in mind that such jurisprudence is often not binding or not binding universally. In addition, precedents of human rights bodies specifically addressing both aspects, the procedural regulation of security detention and in relation to armed conflict, are rare.

The European Court of Human Rights has upheld state security detention during situations described as ‘terrorist campaign[s]’;Footnote ¹⁰⁷ it remains to be seen how the Court would assess whether the measures adopted by the state – after derogation – do or do not go beyond ‘the extent strictly required by the exigencies’Footnote ¹⁰⁸ of a situation characterized as armed conflict. In relation to the ‘war on terror’ and detention at Guantánamo Bay, the Human Rights Chamber for Bosnia and Herzegovina found that the state had breached the European Convention ‘by handing over [persons] into illegal detention by US forces’, as information on the basis for their detention was neither sought nor received.Footnote ¹⁰⁹

Human rights bodies of the Inter-American system have addressed issues relating to armed conflict, but few refer to security detention. In Coard v. US, the Inter-American Commission found detention without any review, during an international armed conflict, ‘incompatible with the terms of the Declaration as understood with reference to art. 78 of Geneva Convention IV’.Footnote ¹¹⁰ The Commission stated that,

In the said case there was no discussion, however, of applicable rules for non-international armed conflict. In 2002 the Commission – in the context of the United States considering ‘itself to be at war with an international network of terrorists’ – adopted precautionary measures requesting the United States ‘to take urgent measures necessary to have the legal status of the detainees at Guantánamo Bay determined by a competent tribunal’ rather than by a political authority, in order to ensure that the detainees ‘are afforded the legal protections commensurate with the status that they are found to possess, which may in no case fall below the minimum standards of non-derogable rights’.Footnote ¹¹²

Application of human rights as lex specialis

When comparing the treaty-based provisions regulating internment in both branches of law, human rights are more elaborate than the sparse treaty-based humanitarian law rules applicable to non-international armed conflict. However, this is not the case when comparing human rights law with humanitarian law applicable to civilians in international armed conflict.Footnote ¹¹³ For example, humanitarian law explicitly guarantees, for civilian internees, a right to appeal and a time frame for periodic review if not released; treaty-based human rights do not specify this with regard to security detention. Moreover, the relevant human rights provisions are derogable, at least under the formal terms of the treaties; these provisions of humanitarian law, at least in occupied territories, are not derogable.Footnote ¹¹⁴ But human rights law does stipulate that the body reviewing the deprivation of liberty must be judicial, whereas humanitarian law provides for either a court or an administrative board in the case of civilians but grants no review at all for prisoners of war, except in determining prisoner-of-war status.Footnote ¹¹⁵

As humanitarian law applicable to non-international armed conflict is silent on the procedural regulation of internment, it would seem clear that in accordance with the lex specialis principle as a maxim of logic, human rights should step in to fill the gap. The ICRC Study appears to adopt this approach when it interprets the humanitarian law rule prohibiting the arbitrary deprivation of liberty through the lens of human rights.Footnote ¹¹⁶ The fact that internees – unlike persons to be attacked – are always under the control of those who detain them, reinforces the human rights approach. In this formalistic application of the lex specialis principle, the only exception where humanitarian law would take precedence is when the parties to a non-international armed conflict agree theretoFootnote ¹¹⁷ or when the government unilaterally concedes prisoner-of-war status to captured fighters. Despite the appeal of this formal lex specialis approach, difficulties remain.

Difficulties involved in applying human rights

The human rights requirement that internment be subject to judicial review – if no derogation is made, or cannot be made as the rule is found to be customarily non-derogable – demonstrates some of these difficulties. One is whether it is realistic to expect states and non-state actors, possibly interning thousands of people, to bring all internees before a judge without delay during armed conflict. If it is not, such an obligation risks severely hampering the effective conduct of war and could thus lead to less compliance with the rules in the long term – for example, summary executions disguised as battlefield killings.

A second concern stems from the differences between state and non-state actors, which have equal obligations under humanitarian law but not under human rights. Even if the question of whether non-state actors are bound by human rights were settled, how is the non-state actor to meet the obligation of judicial review? The question of whether a non-state actor may establish a court remains controversial.Footnote ¹¹⁸ The requirements that there be a legal basis and procedures established by law for internment give rise to the same concern. While human rights themselves set at least two procedural requirements, neither they nor humanitarian law applicable to non-international armed conflict provide a specific legal basis for internment. A state can do so in its domestic law, but how is the non-state actor to establish that legal basis?

Even if human rights are found to be binding on some non-state actors – that is, those ‘capable of fulfilling the conditions to exercise those rights’,Footnote ¹¹⁹ the difficulties may not be fully resolved and additional ones may arise. For example, could a non-state actor derogate from human rights? What is the standard to determine which non-state actor qualifies to do so and which does not? And this approach would not, of course, resolve the difficulties remaining with regard to those non-state actors which do not ‘qualify’.

Application of human rights seems to make it impossible for one party to an armed conflict – the non-state actor – to intern legally. Parties to armed conflicts intern persons, hindering them from continuing to bear arms, so as to gain the military advantage. If the non-state actor cannot legally intern, it is left with little option – for it is a serious violation of humanitarian law to deny quarterFootnote ¹²⁰ – but to release the captured enemy fighters. However, if rules applicable to armed conflict make efficient fighting impossible, they will not be respected, undermining any protection the law provides.Footnote ¹²¹

Apply the humanitarian law of international armed conflicts by analogy?

In view of the complications generated by applying human rights, perhaps the correct solution requires applying the humanitarian law of international armed conflict to non-international armed conflicts by analogy.Footnote ¹²² The humanitarian law applicable to non-international armed conflict indicates that internment occurs in such conflicts, but contains no indication of how it is to be regulated. Such regulation is necessary so that internment can take place in practice. While the provisions regulating internment in international armed conflict are set out according to protected person categories, ‘no fundamental difference between the regimes applicable to the two situations prohibits the application of those same’ provisions, as long as the rules are applied according to the person's function rather than status.Footnote ¹²³ Such a legal analogy is also consistent with the noted gradual erosion of the distinction between the law applicable in international and non-international armed conflicts.

Applied by analogy, the humanitarian law of international armed conflict allows for internment and provides for review procedures. It leaves open the option for the internment review to be carried out by an administrative board or a court. Given the organizational criteria a non-state actor must meet to be considered a party to an armed conflict,Footnote ¹²⁴ any non-state actor should be able to fulfil these obligations, particularly as it can opt for an administrative review procedure rather than review by a court.

The humanitarian law of international armed conflict applies if ‘the government of the State affected by the non-international armed conflict [has] claimed for itself belligerent rights’.Footnote ¹²⁵ While ‘the recognition of belligerency has fallen into disuse as a legal concept’,Footnote ¹²⁶ application by analogy appears to continue to make sense; Common Article 3 moreover urges parties to non-international armed conflicts to agree on such application. The ICRC Study in fact indicates application by analogy in such conflicts of the standards of the Fourth Geneva Convention to civilians and those of the Third Geneva Convention to persons designated as ‘combatants’.Footnote ¹²⁷ Making this distinction between ‘combatants’ and civilians in non-international armed conflict would also be consistent with current discussions by experts on use of the ‘membership approach’ to interpret ‘direct participation in hostilities’ in such conflict.Footnote ¹²⁸ As analogous application does not confer any status, there would still, for example, be no combatant immunity. The Geneva Conventions, while allowing for internment, would therefore not prevent the repression of acts prohibited by domestic law. Nor would application by analogy of the Third Convention to members of armed forces and groups, as suggested by the ICRC Study, entitle them to any review procedure; such procedural regulation could only be found in the Fourth Convention.

Does the analogous application of the law of international armed conflicts sufficiently consider, however, the fundamental distinction between that law and the law of non-international armed conflict – that is, that the rules applicable to international armed conflict generallyFootnote ¹²⁹ apply only to protected person categories, such as prisoners of war or enemy civilians, and that no such categories exist in non-international armed conflict? Even if the distinction in non-international armed conflict could be made by function rather than status, on which criteria should the assessment of a civilian or ‘combatant’ be based? Should ‘combatants’ be measured against the criteria in Article 4 of the Third Convention or Article 44 of Protocol I, or perhaps through the ‘membership approach’?Footnote ¹³⁰ Would Article 5-type tribunalsFootnote ¹³¹ need to be instituted in non-international armed conflicts to make the determination?

Apply the Fourth Convention rather than the Third Convention?

If the Third Geneva Convention is applied by analogy, a participant in hostilities could be detained without any individual determination for the whole duration of the conflict.Footnote ¹³² However, as seen above, it is much more difficult in non-international than in international armed conflicts to determine who is actually a fighter. Such a determination must therefore be made on an individual basis. It is also much harder to determine the actual end of hostilities than in an international armed conflict between states that may conclude a ceasefire or surrender. All this may support application, if at all, of the law of international armed conflict to non-international armed conflict by analogy to the Fourth Convention alone, as there are no combatants and hence no concomitant prisoner-of-war status in non-international armed conflict. Analogy with the Fourth Convention could be founded on a determination of the lex specialis according to the overall systemic purposes of the international legal order. In non-international armed conflict it would avoid internment of persons without review for the duration of the conflict.

Apply both branches of law in parallel?

Can an analogy legally be made to humanitarian law applicable to international armed conflict when doing so displaces specific human rights rules and thus directly overrides the formal lex specialis maxim? As human rights addressing security detention do exist, such an analogy on this issue may be unlike analogies made, for example, to the definition of ‘military objectives’, a term unique to humanitarian law. Furthermore, analogy to the humanitarian law of international armed conflict may not avoid the difficulties raised by human rights, as these may still apply. For example, if humanitarian law procedures applicable to international armed conflict that regulate internment of civilians are inadequate, human rights may be required to fill the gap.Footnote ¹³³

Consideration of the manner in which human rights complement humanitarian law may help to find a solution for some of the difficulties encountered when applying human rights in non-international armed conflicts, particularly to non-state actors.

This approach remains consistent with the understanding that both bodies of law are complementary and implemented through the maxim of lex specialis, and it respects the maxim of lex posterior, as most human rights developed after the main humanitarian law provisions discussed here. Also, the concern about impracticable obligations arising, such as a judicial review of internment without delay in all cases, remains limited, as human rights treaties include derogation clauses providing states with a regulated ‘way out’ in such situations.

However, reliance solely on human rights to compensate for the lack of procedural regulation of internment in non-international armed conflict may offer only a minimal solution, for unless supplemented by customary lawFootnote ¹³⁵ it clarifies the obligations of states only if the state is party to the human rights treaty, and it is limited by any derogation made. In addition (but this issue is not covered in the present article) the extent to which human rights apply extraterritorially is controversial, which weakens the solution relying on the application of human rights law to non-international armed conflicts abroad. Thus human rights may provide no regulation of state internment. As for the non-state actors – if they are bound at all, they will face conceptual difficulties in complying.

So perhaps the solution is not either to apply human rights or to draw an analogy with the humanitarian law of international armed conflict, but to harmonize appropriately both approaches. The recognized relationship between the two branches of law, the objectives of both, as well as the differences between states and non-state actors, may in fact call for this complementary approach.

Application to non-international armed conflicts of the rules of the humanitarian law of international armed conflicts on civilians provides procedures for internment that are binding on both the state and the non-state actor, as well as places a constraint on the basis for internment. These obligations apply equally to all parties to the conflict. Such application does not preclude the corresponding parallel application of human rights. Thus, if application of the latter is required to provide further details about the regulation, for example of civilian internment,Footnote ¹³⁶ consistent with the maxim of lex specialis, human rights may step in and clarify state obligations, particularly with regard to judicial review. While derogation from human rights may still occur, analogous application of the humanitarian law of international armed conflicts – from which no derogation is possibleFootnote ¹³⁷ – would set a baseline below which no derogation from the human rights rules could go, as humanitarian law provisions already apply in situations most threatening to a nation. This complementary approach would ensure procedural protection for interned non-state actors and would bring much needed clarity to the non-state actor's obligations, thus also procedurally protecting members of the state's armed forces captured in non-international armed conflict. The practicality of this approach, however, does not make it legally binding and the concerns mentioned above remain, particularly as to the appropriateness of drawing an analogy to the humanitarian law of international armed conflict and – within that law – to the Fourth Convention rather than the Third Convention.

To sum up, unfortunately no ideal, straightforward solution exists. While the application of human rights is more satisfactory under the formal lex specialis principle, it is unrealistic, particularly for the non-state armed group. Moreover, the content of the applicable human rights is controversial. To apply by analogy the regulation provided for civilians by the humanitarian law of international armed conflicts may therefore correspond better to the overall systemic purposes of both branches. In practice, the only difference between the two approaches is that the humanitarian law approach is satisfied by an administrative review, while the human rights approach stipulates judicial review. Most people detained in relation to a non-international armed conflict would already greatly appreciate having any opportunity at all for an independent and impartial review of their internment. The establishment of guidelines to assess the relationship between humanitarian law and human rights law in a given situation could be helpful, particularly for the practitioner. Such guidelines would help to ensure consistent solutions that do not compromise the two branches' specific objectives and purposes.Footnote ¹³⁸