1. Historical Background

1The First Hague Peace Conference convened in 1899 sought,among other things, the revision of the Brussels Project of 1874. As stated by Graber, both the Convention (II) with Respect to the Laws and Customs of War on Land and its annexed Regulations Respecting the Laws and Customs of War on Land (hereafter: 1899 Hague Regulations) adopted at this conference generally followed the rules laid down in the Brussels Project of 1874. As a consequence of this interlinkage “the discussions and controversies arising during the formulation of the code parallel those at Brussels”.24 Significantly, ambiguous or unsettled aspects of belligerent occupation could not be settled in the twenty-five year period between the Brussels Project and the First Hague Peace Conference. The concept of belligerent occupation adopted in The Hague in 1899 differs only slightly from the one elaborated in the Brussels Project.25 Although the delegates discussed several proposals to revise the definition, they eventually preferred the text of the Brussels Project.26 While the ratifying States were obliged to “issue instructions to their armed land forces, which shall be in conformity with the [1899 Hague Regulations]”,27 many failed or did so inadequately.28

2In 1907, the Second Hague Peace Conference brought together virtually the entire civilised world.29 Its purpose was to revise the 1899 Hague Regulations by clarifying or amending points of detail.30 The provisions on belligerent occupation, however, remained largely unchanged. In particular, the definition of belligerent occupation was not a matter of dispute at the Second Peace Conference and hence the Regulations Respecting the Laws and Customs of War on Land (hereafter: the 1907 Hague Regulations) annexed to Convention (IV) Respecting the Laws and Customs of War on Land brought no clarification in that respect.31

3The development of both the definition and general notion of belligerent occupation thus underwent no noticeable change as a result of the Hague Peace Conferences and remained as vague as it had been thirty-five years earlier. It should also be noted that the concept of occupation as set out in the 1907 Hague Regulations was formulated against the backdrop of the confrontations and battles of the great powers of the 19th century and the Franco-Prussian War of 1870, in particular.32 At that time, war was conducted between governments and their armies and, as a consequence, civilians were usually kept out of war.33 Individuals were not yet subjects of international law and while their treatment remained largely within the exclusive domain of States, the period leading to the 1899/1907 Hague Regulations was also characterised by a trend to limit the competence of the occupying power and towards greater protection of the inhabitants of the occupied territory.34 Still, the increased recognition of individuals as participants and subjects of international law has occurred to a great extent through human rights law in the 20th century.35 The 1907 Hague Regulations therefore primarily regulated the conduct between the armed forces and endeavoured to serve State interests.36

2. The Notion of Belligerent Occupation in the 1907 Hague Regulations

4Under the heading “Military Authority over the Territory of the Hostile State”, Article 42 of the 1907 Hague Regulations puts forward an apparently simple test regarding what constitutes belligerent occupation:

 “Territory is considered occupied when it is actually placed under the authority of the hostile army.
The occupation extends only to the territory where such authority has been established and can be exercised.”37

5The 1907 Hague Regulations emphasise that the existence of belligerent occupation is based on objective circumstances, that is to say that territory (and its population) is “actually” placed under the authority of the enemy army. The fundamental element of a state of belligerent occupation thereby lies within the notion of effective control over the territory of a State by the hostile armed forces of another State. Belligerent occupation within the meaning of the 1907 Hague Regulations is therefore contingent upon the principle of effectiveness.38

6For a state of belligerent occupation to exist it is not necessary that the whole territory of a belligerent State must be occupied. The second paragraph of Article 42 of the 1907 Hague Regulations stipulates that belligerent occupation may be limited to a relatively small part of the enemy’s territory. In addition, the article does not require a minimal (anticipated) duration of the occupation. As a result, even a relatively short period of a foreign presence might lead to a state of belligerent occupation.

3. The Beginning of Belligerent Occupation according to the 1907 Hague Regulations

3.1 Elements of Belligerent Occupation

7As seen above, the concept of belligerent occupation as set out in the 1907 Hague Regulations is based on the principle of effectiveness. From the definition of belligerent occupation one can deduce that it must be “both actual and effective”.39 The UK Manual, for instance, puts forward a two-pronged test indicating the existence of belligerent occupation:

“first, that the former government has been rendered incapable of publicly exercising its authority in that area; and, secondly, that the occupying power is in a position to substitute its own authority for that of the former government.”40

8The two elements required by the 1907 Hague Regulations for belligerent occupation are a) effective control over the enemy territory and b) the establishment of authority.41

a) Effective Control

9The constitutive element of belligerent occupation is effective control. For belligerent occupation to be established, the armed forces that have invaded the enemy’s territory must have gained, as a matter of fact, control over the area concerned through their physical presence.42 Whether or not physical presence of troops is actually required to establish and maintain belligerent occupation has been subject of much controversy since the Brussels Conference of 1874.43 The prevailing opinion, however, prefers the interpretation that enemy troops must be present on the invaded territory in order to establish a state of belligerent occupation.44 On the other hand, it is also accepted that once a state of belligerent occupation has been established, the permanent stationing of troops is not essential for the maintenance of belligerent occupation, provided that enough troops are available to enforce authority in the area.45 The number and type of troops necessary must be assessed on a case-by-case basis and depends on various considerations.46

10This conception seems to be consistent with the discussions held at the 1874 Brussels Project,47 and was subsequently upheld in the Hostage Case in which the American Military Tribunal sitting in Nurembergheld that because the German Armed Forces “could at any time they desired assume physical control of any part of the country” they maintained belligerent occupation of Greece and Yugoslavia even though partisans temporarily controlled parts of these countries.48 Similarly, one of the guidelines put forward by the Trial Chamber of the ICTY in the Naletilić case to determine whether authority has been established requires that “the occupying power has a sufficient force present, or the capacity to send troops within a reasonable time to make the authority of the occupying power felt [emphasis added]”.49

11Lack of clarity also remains with regard to what object that has to be brought under the effective control of the hostile army and its content. Is it just territory over which authority must be established, or is it something else?50 In interpreting the relevant provisions of the 1907 Hague Regulations, particularly Article 43 thereof, Dikker Hupkes concludes, “the government functions of the legitimate authority must be brought under the effective control of the occupant”.51 Furthermore, the occupying power would not need to be in control of all government functions but must be in control of, at a minimum, those functions necessary for the enforcement of governmental authority such as the police and the military.52 According to another author, the control over the invaded territory must be such as to enable the armed forces to “assume the responsibility of an occupying power”, which would include “the ability to issue directives to the inhabitants [...] and to enforce their respect”.53

12Indeed, the substitution of the occupying power’s authority for that of the legitimate government seems to be the most relied upon criterion to assess whether foreign troops occupy the invaded territory in the sense of Article 42 of the 1907 Hague Regulations.54 In the Armed Activities Case, the International Court of Justice (hereafter: ICJ) had to “satisfy itself that the Ugandan armed forces in the DRC [Democratic Republic of the Congo] were not only stationed in particular locations but also that they had substituted their own authority for that of the Congolese Government”.55 On the basis that a Ugandan commander created a new province and appointed its Governor, the ICJ found that Ugandan troops effectively controlled the Ituri region and that Uganda was therefore an occupying power in that part of Congolese territory.56 By contrast, other areas where Ugandan troops were stationed, such as the Kisangani Airport deemed under their “administrative control”, were not considered subject to belligerent occupation in the meaning of Article 42 of the 1907 Hague Regulations.57

b) Military Authority

13Belligerent occupation as understood in the 1907 Hague Regulations calls for the establishment of military authority. This can be deduced from the second paragraph of Article 42 and the title of Section III of the 1907 Hague Regulations.58 At the time when the 1907 Hague Regulations were adopted, it was assumed that the occupant, having gained control, would then establish its authority by introducing “a system of direct administration”.59 Roberts also concludes that “an open and identifiable command structure is thus a central feature of the Hague definition of military occupation”.60 By contrast, the ICJ held in the Armed Activities Case that the establishment of a “structured military administration of the territory occupied” would not be relevant in order to decide whether or not Uganda was an occupying power.61 Instead, the Court contented itself with examining whether “authority was in fact established and exercised”.62 Indeed, the practice of establishing a direct administration seems to have become the exception rather than the rule and a failure to do so will not free an occupying power of the obligation to comply with the rules on occupation.63 On the other hand, the establishment of an occupation administration certainly would facilitate the compliance with the duties of an occupying power.64

3.2 Distinction between invasion and belligerent occupation

14The traditional and predominant conception of a state of belligerent occupation is founded on a strict distinction between invasion and occupation.65 The term “invasion” depicts the phase in which a hostile army penetrates the territory of an enemy State.66 According to this conception, “authority”, and thus belligerent occupation, as required by the 1907 Hague Regulations cannot be established by the mere presence of armed forces on the territory of a hostile State.67 For belligerent occupation to be established, an additional condition must be realised.68 After World War II the American Military Tribunal in the Hostages trial took the view that:

 “Whether an invasion has developed into an occupation is a question of fact. The term invasion implies a military operation while occupation indicates the exercise of governmental authority to the exclusion of the established government. This presupposes the destruction of organized resistance and the establishment of an administration to preserve law and order. To the extent that the occupant’s control is maintained and that of the civil government eliminated, the area will be said to be occupied.”69

15The US Army Field Manual, for instance, describes the difference between invasion and occupation as follows:

 “If resistance is offered, the state of invasion within any portion of a belligerent’s territory corresponds with the period of resistance. If the invasion is unresisted, the state of invasion lasts only until the invader has taken firm control of the area with the intention of holding it. Invasion is not necessarily occupation, although occupation is normally preceded by invasion and may frequently coincide with it. [...] Occupation, on the other hand, is invasion plus taking firm possession of enemy territory for the purpose of holding it [emphasis added].”70

16Similarly, in the Naletilić case the Trial Chamber of the ICTY proposed guidelines providing assistance for determining whether the occupying power has actually established the authority required by the 1907 Hague Regulations for a state of belligerent occupation.71 The Trial Chamber highlighted that “battle areas may not be considered as occupied territory” since one of guidelines would be the surrender, defeat or withdrawal of the enemy’s forces.72 On the other hand, once a state of belligerent occupation has been established, “sporadic local resistance, even successful,” does not end or negate it.73

17A state of belligerent occupation is thus interpreted as “a transitional period following invasion and preceding the agreement on the cessation of the hostilities”.74 According to this “traditional” conception, invasion and belligerent occupation are considered as two distinct categories calling for two distinct sets of rules.

18Granted, resistance by armed forces of the invaded country is a strong indication that authority has not yet fully passed to the invading forces. Yet, one problem of a strict distinction between invasion and belligerent occupation is that the transition from one concept to the other may be gradual and without a clear dividing line. The US Army Field Manual thus acknowledges that belligerent occupation “[...] may frequently coincide with [invasion]”.75 Furthermore, once a state of belligerent occupation has been established, occupation and hostilities as a result of local resistance may co-exist.76 In other words, a state of belligerent occupation does not exclude the parallel applicability of the rules governing hostilities. The possibility of a parallel application of the law of belligerent occupation and the rules governing the conduct of hostilities further complicates the determination of the exact point in time when an invasion ends and a state of belligerent occupation begins.