19. For the reasons set out in the Joint Separate Opinion of Judge McDonald and Judge Vohrah and in the Separate and Dissenting Opinion of Judge Li, the majority of the Appeals Chamber finds that duress does not afford a complete defence to a soldier charged with a crime against humanity and/or a war crime involving the killing of innocent human beings. 

The Joint Separate Opinion of Judge McDonald and Judge Vohrah sets out the reasons as follows:

34. Superior orders and duress are conceptually distinct and separate issues and often the same factual circumstances engage both notions, particularly in armed conflict situations.  We subscribe to the view that obedience to superior orders does not amount to a defence per se but is a factual element which may be taken into consideration in conjunction with other circumstances of the case in assessing whether the defences of duress or mistake of fact are made out.

35. […] As obedience to superior orders may be considered merely as a factual element in determining whether duress is made out on the facts, the absence of a superior order does not mean that duress as a defence must fail.

36. […] [W]e would like to reiterate our view that obedience to superior orders is merely a factual circumstance to be considered when determining whether the defence of duress is made out on the merits.  The fact that the Appellant obeyed an order of a superior does not go to the preceding legal question of whether duress may at all be pleaded as a defence.

In order to decide on the international customary law nature of duress as a defence to the killing of innocent persons, the Joint Separate Opinion of Judge McDonald and Judge Vohrah carried out a review of the case-law, state practice and opinio juris in paragraphs 41 to 49 of their Joint Opinion and concluded:

50. Not only is State practice on the question as to whether duress is a defence to murder far from consistent, this practice of States is not, in our view, underpinned by opinio juris.  Again to the extent that state practice on the question of duress as a defence to murder may be evidenced by the opinions on this question in decisions of national military tribunals and national laws, we find quite unacceptable any proposition that States adopt this practice because they “feel that they are conforming to what amounts to a legal obligation” at an international level[1].

55. In light of the above discussion, it is our considered view that no rule may be found in customary international law regarding the availability or the non-availability of duress as a defence to a charge of killing innocent human beings.  The post-World War Two military tribunals did not establish such a rule.  We do not think that the decisions of these tribunals or those of other national courts and military tribunals constitute consistent and uniform state practice underpinned by opinio juris sive necessitatis.

The Joint Separate Opinion of Judge McDonald and Judge Vohrah then analysed the general principles of law recognised by civilised nations in order to shed light to the issue of duress in paragraphs 56 to 65 and concluded that:

66.        Having regard to the above survey relating to the treatment of duress in the various legal systems, it is, in our view, a general principle of law recognised by civilised nations that an accused person is less blameworthy and less deserving of the full punishment when he performs a certain prohibited act under duress.  We would use the term “duress” in this context to mean “imminent threats to the life of an accused if he refuses to commit a crime” and do not refer to the legal terms of art which have the equivalent meaning of the English word “duress” in the languages of most civil law systems.  This alleviation of blameworthiness is manifest in the different rules with differing content in the principal legal systems of the world as the above survey reveals.  On the one hand, a large number of jurisdictions recognise duress as a complete defence absolving the accused from all criminal responsibility. On the other hand, in other jurisdictions, duress does not afford a complete defence to offences generally but serves merely as a factor which would mitigate the punishment to be imposed on a convicted person.  Mitigation is also relevant in two other respects.  Firstly, punishment may be mitigated in respect of offences which have been specifically excepted from the operation of the defence of duress by the legislatures of some jurisdictions.  Secondly, courts have the power to mitigate sentences where the strict elements of a defence of duress are not made out on the facts.

It is only when national legislatures have prescribed a mandatory life sentence or death penalty for particular offences that no consideration is given in national legal systems to the general principle that a person who commits a crime under duress is less blameworthy and less deserving of the full punishment in respect of that particular offence.

67.        The rules of the various legal systems of the world are, however, largely inconsistent regarding the specific question whether duress affords a complete defence to a combatant charged with a war crime or a crime against humanity involving the killing of innocent persons.  As the general provisions of the numerous penal codes set out above show, the civil law systems in general would theoretically allow duress as a complete defence to all crimes including murder and unlawful killing.  On the other hand, there are laws of other legal systems which categorically reject duress as a defence to murder.   Firstly, specific laws relating to war crimes in Norway and Poland do not allow duress to operate as a complete defence but permit it to be taken into account only in mitigation of punishment.  Secondly, the Ethiopian Penal Code of 1957 provides in Article 67 that only “absolute physical coercion” may constitute a complete defence to crimes in general.  Where the coercion is “moral”, which we would interpret as referring to duress by threats, the accused is only entitled to a reduction of penalty.  This reduction of penalty may extend, where appropriate, even to a complete discharge of the offender from punishment.  Thirdly,  the common law systems throughout the world, with the exception of a small minority of jurisdictions of the United States which have adopted without reservation Section 2.09 of the United States Model Penal Code, reject duress as a defence to the killing of innocent persons. 

72. It is clear from the differing positions of the principal legal systems of the world that there is no consistent concrete rule which answers the question whether or not duress is a defence to the killing of innocent persons.  It is not possible to reconcile the opposing positions and, indeed, we do not believe that the issue should be reduced to a contest between common law and civil law. We would therefore approach this problem bearing in mind the specific context in which the International Tribunal was established, the types of crimes over which it has jurisdiction, and the fact that the International Tribunal’s mandate is expressed in the Statute as being in relation to “serious violations of international humanitarian law”.

See also paragraphs 68–71.

After concluding that it is not possible to reconcile the opposing positions of the principal legal systems of the world on the question whether or not duress is a defence to the killing of innocent persons, Judge McDonald and Judge Vohrah held:

72. […] We would therefore approach this problem bearing in mind the specific context in which the International Tribunal was established, the types of crimes over which it has jurisdiction, and the fact that the International Tribunal’s mandate is expressed in the Statute as being in relation to “serious violations of international humanitarian law”.

75. […] The purview of the International Tribunal relates to war crimes and crimes against humanity committed in armed conflicts of extreme violence with egregious dimensions.  We are not concerned with the actions of domestic terrorists, gang-leaders and kidnappers.  We are concerned that, in relation to the most heinous crimes known to humankind, the principles of law to which we give credence have the appropriate normative effect upon soldiers bearing weapons of destruction and upon the commanders who control them in armed conflict situations.  The facts of this particular case, for example, involved the cold-blooded slaughter of 1200 men and boys by soldiers using automatic weapons.  We must bear in mind that we are operating in the realm of international humanitarian law which has, as one of its prime objectives, the protection of the weak and vulnerable in such a situation where their lives and security are endangered. Concerns about the harm which could arise from admitting duress as a defence to murder were sufficient to persuade a majority of the House of Lords and the Privy Council to categorically deny the defence in the national context to prevent the growth of domestic crime and the impunity of miscreants.  Are they now insufficient to persuade us to similarly reject duress as a complete defence in our application of laws designed to take account of humanitarian concerns in the  arena of brutal war, to punish perpetrators of crimes against humanity and war crimes, and to deter the commission of such crimes in the future?   If national law denies recognition of duress as a defence in respect of the killing of innocent persons, international criminal law can do no less than match that policy since it deals with murders often of far greater magnitude.  If national law denies duress as a defence even in a case in which a single innocent life is extinguished due to action under duress, international law, in our view, cannot admit duress in cases which involve the slaugher of innocent human beings on a large scale.  It must be our concern to facilitate the development and effectiveness of international humanitarian law and to promote its aims and application by recognising the normative effect which criminal law should have upon those subject to them.  Indeed, Security Council resolution 827 (1993) establishes the International Tribunal expressly as a measure to “halt and effectively redress” the widespread and flagrant violations of international humanitarian law occurring in the territory of the former Yugoslavia and to contribute thereby to the restoration and maintenance of peace.

80. […] The approach we take does not involve a balancing of harms for and against killing but rests upon an application in the context of international humanitarian law of the rule that duress does not justify or excuse the killing of an innocent person.  Our view is based upon a recognition that international humanitarian law should guide the conduct of combatants and their commanders.  There must be legal limits as to the conduct of combatants and their commanders in armed conflict.  In accordance with the spirit of international humanitarian law, we deny the availability of duress as a complete defence to combatants who have killed innocent persons.  In so doing, we give notice in no uncertain terms that those who kill innocent persons will not be able to take advantage of duress as a defence and thus get away with impunity for their criminal acts in the taking of innocent lives.

88. After the above survey of authorities in the different systems of law and exploration of the various policy considerations which we must bear in mind, we take the view that duress cannot afford a complete defence to a soldier charged with crimes against humanity or war crimes in international law involving the taking of innocent lives.  We do so having regard to our mandated obligation under the Statute to ensure that international humanitarian law, which is concerned with the protection of humankind, is not in any way undermined.

See also paras. 73-74, 75 (part not cited above), 76-79, 80 (part not cited above), 81-87.

In his Separate and Dissenting Opinion Judge Li stated the following:

5. From a study of decisions [of the United States Military Tribunals at Nürnberg in proceedings under the Control Council Law No. 10 and those of Military Tribunals and/or Courts set up by various other allied countries for the same purpose for the same purpose] the following principles can be obtained:  as a general rule, duress can be a complete defence if the following requirements are met, (a) the act was done to avoid an immediate danger both serious and irreparable, (b) there was no other adequate means to escape, and (c) the remedy was not disproportionate to evil.  To this general rule there is an important exception:  if the act was a heinous crime, for instance, the killing of innocent civilians or prisoners of war, duress cannot be a complete defence, but can only be a ground of mitigation of punishment if justice requires.

8. In my view, both the rule and the exception are reasonable and sound, and should be applied by this International Tribunal. However, as this appeal case is concerned with the applicability of the exception, a few more words should be said about it.

In the first place, the main aim of international humanitarian law is the protection of innocent civilians, prisoners of war and other persons hors de combat.  As the life of an innocent human being is the sine qua non of his existence, so international humanitarian law must strive to ensure its protection and to deter its destruction.  Admission of duress as a complete defence or justification in the massacre of innocent persons is tantamount to both encouraging the subordinate under duress to kill such persons with impunity instead of deterring him from committing such a horrendous crime, and also helping the superior in his attempt to kill them.  Such an anti-human policy of law the international community can never tolerate, and this International Tribunal can never adopt.

Second, the present municipal laws of various countries regarding the propriety or necessity of recognising the exception to the rule, as shown above, are divergent.  On the one hand, the legal systems of the British Commonwealth and some civil-law systems admit the exception.  On the other hand, some other civil-law systems do not provide for it.  In such circumstances, this International Tribunal cannot but opt for the solution best suited for the protection of innocent persons.

See also paras. 3-4, 6-7 and 9-10 of the Separate and Dissenting Opinion of Judge Li.

582. [I]f the defendant raises the issue of lack of mental capacity, he is challenging the presumption of sanity by a plea of insanity.  That is a defence in the true sense, in that the defendant bears the onus of establishing it – that, more probably than not, at the time of the offence he was labouring under such a defect of reason, from disease of the mind, as not to know the nature and quality of his act or, if he did know it, that he did not know that what he was doing was wrong.[1]  Such a plea, if successful, is a complete defence to a charge and it leads to an acquittal.  It is submitted by Landžo that Rule 67(A)(ii) has also made diminished mental responsibility a complete defence to any charge (or has perhaps recognised it as such),[2] an argument which the Trial Chamber had accepted.[3]

The Appeals Chamber examined in paragraphs 583, 585-588 the ICTY Statute and Rules of Procedure and Evidence, the English Homicide Act of 1957, the partial defence of diminished responsibility that originated in Scotland in the 19th century, Article 31(1)(a) of the ICC Statute, and the relevant penal laws in many other countries.

590. […] The Appeals Chamber accepts that the relevant general principle of law upon which, in effect, both the common law and the civil law systems have acted is that the defendant’s diminished mental responsibility is relevant to the sentence to be imposed and is not a defence leading to an acquittal in the true sense.  This is the appropriate general legal principle representing the international law to be applied in the Tribunal.  Rule 67(A)(ii)(b) must therefore be interpreted as referring to diminished mental responsibility where it is to be raised by the defendant as a matter in mitigation of sentence.  As a defendant bears the onus of establishing matters in mitigation of sentence, where he relies upon diminished mental responsibility in mitigation, he must establish that condition on the balance of probabilities – that more probably than not such a condition existed at the relevant time.

Martić claimed that his actions were in response to persecution of the Serb population by the Croatian authorities.  Accordingly, he submitted defences of reciprocity or tu quoque; reprisal; and self-defence. 

Similarly, the Appeals Chamber found that self-defence could not be used to justify deliberately targeting a civilian population.

268. As for Martić’s alternative argument that the shelling of Zagreb was a lawful military action conducted in self-defence,[1] the Appeals Chamber recalls that “whether an attack was ordered as pre-emptive, defensive or offensive is from a legal point of view irrelevant […]. The issue at hand is whether the way the military action was carried out was criminal or not.”[2] […] As Martić has failed to show any error in the Trial Chamber’s conclusion that he deliberately targeted the civilian population of Zagreb,[3] his argument that the shelling of Zagreb was conducted in self-defence must fail. The Appeals Chamber takes note of Martić’s arguments in his concluding statement at the appeal hearing that “the Serbs were not aggressors but rather defended themselves in a situation when the United Nations made no attempt to protect them […].”[4] However, in particular in light of the fact that the prohibition against attacking civilians is absolute,[5] the Appeals Chamber fails to see how this claim could justify Martić’s actions in relation to the shelling of Zagreb.

Martić claimed that his actions were in response to persecution of the Serb population by the Croatian authorities.  Accordingly, he submitted defences of reciprocity or tu quoque; reprisal; and self-defence.

The Appeals Chamber held that reciprocity or tu quoque could not be used to justify a serious violation of international humanitarian law.

109. Martić argues that Serbs in SAO Krajina, for historical reasons, had a right to claim self-determination in accordance with international law and that instead of being able to exercise this right, they ended up being persecuted by the Croatian authorities in the 1990s in a way similar to the persecutions and massacres of Serbs by Croats during the 1940s.[1]

[…]

111. To the extent that Martić’s argument is an attempt to plead a defence of tu quoque, i.e., to plead that the acts for which he was found responsible should not be considered criminal because they were in response to crimes committed against him and his people, it must be rejected. It is well established in the jurisprudence of the Tribunal that arguments based on reciprocity, including the tu quoque argument, are no defence to serious violations of international humanitarian law.[2]