The Legal Regulation of War

• Pages: 161-192
• Author: Beth Van Schaack,Ronald C. Slye

161

Chapter 6

THE LEGAL REGULATION OF WAR

As discussed in more detail in Chapter 1, the law of war has

historically encompassed two main foci: the jus ad bellum and the jus

in bello. The former addresses the legality of going to war and

historically took the form of theological and then secular “just war”

theories; the latter concedes the de facto existence of a conflict and

seeks to regulate belligerent conduct within it, regardless of the

origins of the violence in the first place. Although some of the world’s

greatest minds have grappled with establishing standards for

determining when states had the right to go to war, by the late

nineteenth century, the right to wage war began to be viewed as an

inherent, if not inevitable, incident of state sovereignty. Further

development of the jus ad bellum was all but eclipsed by prolific

developments in jus in bello. Nonetheless, these two approaches to

regulating warfare converged in the charters of the World War II

international tribunals, which adjudicated violations of both bodies

of law as crimes giving rise to individual criminal responsibility—

even though neither body of law was necessarily designed at that

time to be applied in a courtroom.

In the postwar period, violations of jus ad bellum (referred to as

“crimes against the peace” at Nuremberg and Tokyo) all but

disappeared from the pantheon of international criminal law (ICL).

Instead, Article 2(4) of the U.N. Charter addressed states—rather

than individuals—and prohibited the “threat or use of force against

the territorial integrity or political independence of any state, or in

any other manner inconsistent with the Purposes of the United

Nations.” Under the U.N. Charter regime, breaches of this provision

give rise to state, rather than individual criminal, responsibility. For

their part, war crimes were further codified in the 1949 Geneva

Conventions.

Contemporary international law now views the conceptual

distinction between the jus ad bellum and the jus in bello as

axiomatic: The legal evaluation of the conduct of hostilities is an

inquiry entirely independent from the legal evaluation of the

lawfulness of the resort to armed force. Accordingly, a just (or lawful)

war may be fought unlawfully, and an unjust (or unlawful) war may

be fought lawfully. Under the jus in bello, by consequence, all parties

are treated equally, regardless of who initiated the armed conflict

and their reasons for doing so. The belligerents of all sides are

entitled to humane treatment if captured and the civilians on all

sides are immune from direct targeting. Indeed, the International

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INTERSECTIONS

Pt. II

Committee of the Red Cross (ICRC) remains strictly agnostic about

the cause(s) of any armed conflicts in which it operates while

carefully scrutinizing their consequences. That said, there is an

intuitive appeal to the position, still advocated by some, that any act

of armed force committed within the context of an unlawful war

should ipso facto be treated as a war crime. On the flip side, many

groups fighting against what they consider to be oppressive, racist,

or occupier states continue to argue that any act committed in

furtherance of such a just war must itself also be deemed just and

lawful.

Although crimes against the peace have to date merited only a

short chapter in the annals of ICL, the idea that the resort to war

itself is a criminal act has become more than a historical footnote. In

2017, the International Criminal Court’s (ICC) Assembly of States

Parties activated amendments adding the crime of aggression—the

modern lexicon for crimes against the peace—to the subject matter

jurisdiction of the Court, although the crime has yet to be

adjudicated. As such, the jus ad bellum and jus in bello have now

been reunited in the Statute of the ICC.

This chapter briefly traces some high points in the development

of the penal components of these two bodies of law. It then presents

the basic framework for understanding the contemporary law of

aggression and then war crimes, noting areas in the law that remain

in flux. Underlying this chapter is a rich legacy of legal rules aimed

at the regulation of hostilities that belies the claim by Cicero that

silent enim leges inter arma—the laws are silent among those at war.

A. Jus Ad Bellum

1. Crimes Against Peace: The Original Crime of Aggression

The Charters for both the Nuremberg and Tokyo Tribunals

contained the charge of “crimes against the peace” alongside the

charges of war crimes and crimes against humanity. The postwar

architects of international justice defined crimes against the peace

somewhat tautologically at Article 6(a) as “planning, preparation,

initiation or waging of a war of aggression, or a war in violation of

international treaties, agreements or assurances.”

1

In addition, the

two tribunal charters allowed for the prosecution of individuals for

their “participation in a common plan or conspiracy” to commit

aggression. Count One of the Nuremberg Indictment charged all the

defendants with conspiring to commit crimes against the peace.

Count Two charged all but five defendants with actually committing

crimes against the peace. All but four defendants were charged with

1

Charter of the International Military Tribunal art. 6(a), Aug. 8, 1945, 59

Stat. 1546, 82 U.N.T.S. 279.

Ch. 6

THE LEGAL REGULATION OF WAR

163

war crimes in Count Three. At Tokyo, all the defendants were

charged with so-called Class A crimes—the crime of executing a

common plan or conspiracy to wage aggressive war or wars in

violation of international law—as a jurisdictional prerequisite.

Although the World War II defendants did not submit to the

equally novel crimes against humanity charge without objection, the

crimes against the peace charge was the most controversial element

of the Charters at the time. Both sets of defendants argued that the

concept of crimes against the peace violated the principle of legality,

because war had never before been criminalized in international law,

so the prohibition against crimes against the peace in the two

Charters was, in effect, ex post facto legislation. As is discussed more

fully in Chapter 5 on the defense of nullum crimen sine lege, the

tribunals ruled that the acts of aggression proven at trial were

unlawful, and thus criminal, under extant treaties and customary

norms, although none of these sources expressly provided for

criminal penalties in the event of a breach. The Indian judge at

Tokyo, Justice Radhabinod Pal, articulated a different critique: that

the victorious allies sought suddenly to criminalize the very acts that

had brought them to power in the first place during the age of

imperialism and colonialization (with India gaining independence

only in 1947). In his dissent, he noted:

Certainly dominated nations of the present day status quo

cannot be made to submit to eternal domination only in the

name of peace. . . . The part of humanity which has been

lucky enough to enjoy political freedom can now well afford

to have the deterministic ascetic outlook of life, and may

think of peace in terms of political status quo. But every

part of humanity has not been equally lucky and a

considerable part is still haunted by the wishful thinking

about escape from political dominations. . . . To them the

present age is faced with not only the menace of

totalitarianism but also the actual plague of imperialism.

2

Justice Pal’s dissent, which until recently was relatively obscure and

even difficult to find, has enjoyed increased interest from, among

others, critics from the so-called Global South, who challenge the

history and power imbalances embedded in the current international

legal system.

3

2

U.S.A. v. Araki, Sadai et al., Judgment of the Honorable Mr. Justice Pal, in

DOCUMENTS ON THE TOKYO INTERNATIONAL MILITARY TRIBUNAL 809, 910 (Neil Boister

& Robert Cryer eds., 2008).

3

Some of these critics are loosely organized under the banner of TWAIL

(Third World Approaches to International Law). For a good introduction to TWAIL

and its critique of international criminal law, see Symposium on TWAIL Perspectives

on ICL, IHL, and Intervention, 109 AJIL UNBOUND 252 (2015). See also Shantanu