What is the extent of states’ right to use armed force in self-defence?
This question cannot be answered without first defining what is meant by, ‘war’; by no means a straightforward task in academia. For the purposes of this document however, we shall go by Oppenheim’s relatively palatable definition that it is, “…a contention between two or more States, through their armed forces, for the purposes of overpowering each other and imposing such conditions of peace as the victor pleases.” For the sake of avoiding mixed interpretation based on semantics, the phrases, ‘war’ and ‘conflict’ are used interchangeably throughout with no separate meaning unless otherwise stated. Jus ad Bellum (the law toward war) shall be the primary focus of this paper though Jus in Bello (the law of war) shall also be addressed.
Jus ad Bellum
In examining what constituted a right to engage in war, the academic Paul Christopher referenced Grotius and Augustine in coming up with a list of parameters which could be said to give rise to a just war. He noted proportionality of actions relative to cost, suggested that a likelihood of success was required, war may only be declared by a legitimate authority (and must indeed be declared), must only be engaged upon with the best of intentions and should always be a last resort. It is not hard to find fault with at least one of his requirements. The concept of a ‘just war’ is not a new one by any stretch of the definition. Indeed it is more accurate to say that the concept is as old as conflict itself with scholars such as Vattel noting that all those involved in war assert the righteousness of their actions.  It is easily arguable that the actions of the Allied forces in the Second World War were entirely just but Hitler and his supporters also had no doubt as to the justification behind their own. Vattel went on to say that in order to confront such partisanship, a voluntary law of nations must be established so as to provide a mechanism for objective establishment of justification.
Modern Examples of International War Law
The first modern example of this in action was perhaps post World War I with the creation of the League of Nations Covenant in 1919, specifically Articles 10 and 12 which note that in the furtherance of the protection of independence of member states, any conflict which might arise between them would be submitted to the jurisdiction of the League of Nations Council who would rule on the matter. Interestingly this was only to apply to cases involving member states and it may be argued either that this was an action of international selfishness – only those ‘in the club’ were to be afforded such mechanisms – or rather the more pragmatic reality that even the idealism behind the League acknowledged the political difficulties in arbitrating conflicts between states which did not acknowledge the sovereignty of the organisation; an issue which still plagues modern organisations such as the United Nations.
We may also note the Kellogg-Briand Pact (also named the World Peace Act) signed by the main protagonists of World War I which forbade war. Notably it did not specify ‘aggressive war’ but rather all war. Again one may see this as either an explicit denouncement of the idea of a just war or simply the practical fact that there is no such thing as a ‘non-aggressive war’.
The United Nations
Having already mentioned the more modern United Nations, it is appropriate to note that Article 2(4) of the United Nations Charter also prohibits war, though in slightly different terms. Stating that States must refrain from, “…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”, the Article does not explicitly forbid war against non-member states or war which may uphold the purposes of the United Nations. For the third time in a short while we can once more see dual interpretations; either military action can be justified if it is seen to uphold the values of the United Nations or the (ideally) peaceable nature of the United Nations prohibits war of any sort. The latter is a romantic notion but once more pragmatism must be brought forth; the truth is that the nature of Human existence is such that short of an evolution into a utopian Star Trek-like future where all work for the betterment of the whole, conflict is unavoidable and as such the interpretation in this case must be the former.
In fact whilst wishing for the latter definition to hold true may well be understandable, reasonable it is not and this is reflected by scholars such as Franck who wrote in 1970 that, “…the high minded resolve of Article 2(4) mocks us from its grave.” Acknowledging the admirable intent behind the rules Franck went on to say that they were predicated on the false assumption that those alliances made in the aftermath of World War II would hold firm, and the advent of nuclear warfare made the spectre of armed conflict so horrific as to be unthinkable from thereon in. This of course, turned out not to be the case.
Perhaps then, it was with more foresight than Article 2(4) suggests that Article 51 was written, specifically allowing for military action to be taken by member states as self defence in response to an armed attack though Henkin wrote that despite this exception the belief that states were “…as free to indulge [in war] as ever…” had been accepted as customary law. This was later confirmed by the International Court of Justice in Nicaragua v USA however that case is perhaps more noteworthy as a result of its aftermath given that the United States formally denied the jurisdiction of the Court and rather less formally, blatantly ignored a decision which went against it even going so far as to block the enforcement of the Court’s decision which related to the removal of illegally placed US mines. This failure of international law leading Anthony D’Amato to state in reflection that, “”…law would collapse if defendants could only be sued when they agreed to be sued”, is by no means an exception.
The 2003 Iraq Invasion
In 2003 the United States and a coalition of nations invaded the sovereign nation of Iraq, this being probably the most high profile example of modern law concerning warfare in action. The United Nation Security Council unanimously passed Resolution 1441 (Resolutions having been accepted by the ICJ as having binding effect) which text noted that Iraq posed a threat to, “…international peace and security.” Previously the Security Council had passed Resolution 678 which made allowance for member states to take, “…all necessary means…” to uphold Resolution 660.
Resolution 660 (passed concerning the Iraqi invasion of Kuwait in 1990) itself had used the phrase “…breach of international peace and security…” and demanded that Iraq withdraw its troops. Following this Resolution 678 explicitly allowed for military action in that case with the goal of protecting the independence of Kuwait, a member state. It was later argued that the language used in this Resolution despite being specifically concerned with this situation could be used to justify military action in later conflicts such as the 2003 invasion. 
Arguments were made opposing this interpretation, not least by then UN Secretary Kofi Annan but the fact is that the invasion proceeded and at the time of writing not one person has been prosecuted for war crimes as a direct result of the invasion itself (as opposed to actions taken during the occupation). This would either suggest that where there is a real, or perhaps even perceived threat to international security regardless of the specific states involved, military action can be justified if undertaken by a member of the United Nations or that the UN is incapable of policing these matters and so the right to undertake in military action is determined by individual states on their own behalf.
Against Article 2(4)
The above being said it is worthwhile to return to Article 51 and examine the exact wording. Utlisation of the word, ‘inherent’ in describing the right to self defence puts forth the convincing argument that this right was neither established nor limited by the Charter. Given this the question becomes when such a right may be employed and given the legal wrangling surrounding the 2003 Iraq Invasion it may well be inferred that this right may be utilised not only in response to armed attack but in anticipation of one, further widening the scope of the exception. Certainly it seems to this author the height of absurdity to only allow action in defence of a nation’s populace once that population has already been adversely and/or irrevocably affected by the aggression of another. The view is contended however by Grotius who wrote, “That the possibility of being attacked confers the right to attack is abhorrent to every principle of equity. Human life exists under such conditions that complete security is never guaranteed to us.” Despite the age of Grotius’ writings, it is a viewpoint still evidenced in international opinion.
Article 51 is not the only exception to Article 2(4) however. Article 53 not only allows for the establishment of enforcement agencies acting under the Security Council’s supervision, but makes reference to actions that may be taken against ‘enemy states’; actions which may be taken absent the direct authorisation of the Security Council. Article 53’s effect can most obviously be seen in Article 5 of the North Atlantic Treaty 1949 where it is noted both that an attack against one signatory is to be perceived as an attack upon all, and also that the North Atlantic Treaty Organisation (which the Treaty established) could utilise such action as it felt necessary to maintain the peace of the North Atlantic area. Furthermore the Article specifically notes that these actions may include, “…the use of armed force.” Perhaps of note is the fact that all such actions must be reported to the Security Council but given the above there is now no room whatsoever for the argument that States are forbade from waging war, regardless of the intent of Article 2(4).
This position has been challenged, not least by Henkin who wrote in 1971 in direct response to Franck that though Article 2(4)’s condition was grave, reports of its death were as exaggerated as those of Twain’s death. It is respectfully suggested here that even before the example of 2003, Article 2(4) lived only as an idealistic dream with no more direct legal effectiveness than the American Declaration of Independence, neither being the raison d’être of the UN nor one of its fundamental tenants. It may well be an admirable wish to outlaw war not least because it will rescue us from reams of depressing poetry, but the UN’s legal actions from its creation through to the modern day demonstrate that it neither has nor does see this as the practical reality.
The UN’s jurisdiction
As has been evidenced above, debate on this issue typically centres around the law as seen, acknowledged and enacted by the United Nations and its member states for obvious reasons. However vast it might be though, the UN’s jurisdiction is not universal. Neither Kosovo, Vatican City nor Taiwan are represented as member states and in the case of the latter it is as a result of a complex situation which has threatened to elevate to military action on more than one occasion. Without devolving into a discussion on the nature of Taiwan’s independence, the question arises as to what rights states who are not UN members have to use force in self defence and whether the actions employed to protect member states extend to those ‘outside the club’.
An initial reading of Article 2(4) would suggest that this is not the case however the irrelevance of that provision has already been discussed. If China seeing the situation as an internal dispute were to invade Taiwan, the UN which has repeatedly sat on the fence regarding the island’s independence would have to take a stand one way or the other. The US which has traded extensively with Taiwan (including the sale of materiel such as fighter planes) and has an evidenced record of proactive military engagement publically built on the premise of self-determination would perhaps be inclined to intervene or may be put off by the balance of power in such a conflict. That is to say that despite the fact that the US spends more on its military than the next ten nations combined, the armed forces of China are of infinitely greater strength and capability than those of Iraq, Kosovo or Afghanistan. It is also a nuclear power.
This hypothetical is not brought up merely to engage in flights of fancy but to suggest there is perhaps one element of the thinking behind Article 2(4) that remains true. There have been no shortage of armed conflicts since the culmination of World War II but especially in the last three decades, these almost entirely have been relatively small scale events without the, however faint, threat of nuclear action by both sides present (India and Pakistan being the most frightening exception). The idea of all out conflict between the United Kingdom and France or the United States and Russia is almost unimaginable so far has Man’s capability for destruction evolved. Perhaps then it can be argued against Franck that while accepting his premise that war is inevitable, the prospect of World War III as envisaged in the 80s is now no more than a flight of fantasy and so the spirit of Article 2(4) is upheld in that another great war is prevented. Regardless of whether this be the case or not however, it is the spirit in which it was written we discuss; not the effectiveness of its implementation.
Jus in Bello
Beyond the initialisation of war, the right of States to use whatever means they feel necessary in self defence is not limitless. There are numerous rules governing conduct during conflict which are required by the nature of war itself. As Rubin stated, “Almost by definition, war is composed of a series of acts which are ordinarily criminal by nature: killings, assaults, deprivations of liberty and destruction of property.”
In 1868 the St Petersburg Declaration was the first modern attempt to limit certain types of weapons use in warfare, specifically those weapons which caused ‘unnecessary suffering’ and that goal is mirrored in modern attempts. The Hague Conference of 1907 produced the Convention Respecting the Laws and Customs of War on Land which stated amongst many other provisions that occupying powers may not forsake the respect of life (Article 46) and may not pillage (Article 47); tenets that are still seen today in law. The most famed examples of law governing wartime action are the Geneva Conventions of 1949 which most directly deal with treatment of the sick and wounded and prisoners of war; an attempt to maintain an element of Humanity in our most inhumane practice.
The 1980 UN Convention on Conventional Weapons banned the use of undetectable fragmentation weapons, more specifically landmines as well as incendiary weapons and blinding laser weapons. Chemical weapons have been the subject of various bans since 1899 and more recently legislation can be seen in the 1992 Convention on the Prohibition of the Development, Production, Stockpiling and Use of Chemical Weapons and on Their Destruction. Interestingly, nuclear weapons are not specifically outlawed and the doctrine of proportionality may well be said to allow their use when a state is threatened with nuclear attack. One wonders what Grotius might have made of reactionary defence had he been exposed to the nuclear age. That being said, numerous provisions of other laws can be argued to forbid their use. ‘Unnecessary Suffering’ was banned by the 1868 St Petersburg Declaration and 1907 Hague Article 23(e), the latter also banning poisonous weapons. Longterm Environmental Damage is banned by the 1977 Geneva Protocols Article 55 and perhaps most seriously, the 1949 Geneva Civilians Conventions specifies that protected persons must be distinguished from combatants.
There can be no denying that in cetain situations, more specifically in the name of self defence, Military action can not only be morally justified, but legally as well. Despite the limp-wristed nature of Article 2(4) its intent is felt throughout international law and military action is not encouraged; it is of course seen as a last resort. Despite this however, the contradictory nature of international law and the various interpretations that can be drawn from it (as seen in the 2003 Iraq invasion) mean that the specific rights afforded a State are unclear. Certainly the question stands that if a nuclear power violates what are collectively seen to be its war rights under international law, what effective recourse is there? Perhaps then, the rights of states to wage war are based not on international law at all, but rather their military superiority.
-  L.F.L. Oppenheim, Vol II, quoted in British Manual Of Military Law, Part III at p.5, f.n.2
-  Paul Christopher, The Ethics of War and Peace, (Prentice Hall, 2nd Ed. 1999) at chap. 6, pp. 81-91
-  Emerich De Vattel, Droit dens Gens trans. Laws of Nations, 1758
-  Franck, Who Killed Article 2(4)? 64 AJIL (1970) 809
-  Henkin, The Reports of the Death of Article 2(4) are Greatly Exaggerated, 65 AJIL (1971) 544
-  Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Jurisdiction and Admissibility, 1984 ICJ REP. 392 June 27, 1986
-  Anthony D’Amato, NICARAGUA AND INTERNATIONAL LAW: THE “ACADEMIC” AND THE “REAL”, 79 American Journal of International Law 657 (1985) (Code A85d)
-  S/RES/1441
-  Legal Consequences for States of the Continued Presence of South Africa in Namibia (South West Africa) Notwithstanding Security Council Resolution 276 ICJ Rep 16
-  S/RES/678
-  S/RES/660
-  Declassified opinion of the Attorney General on Iraq Resolution 1441 to the Prime Minister, archived from the original <http://web.archive.org/web/20050428194646/http://www.number-10.gov.uk/files/pdf/Iraq+Resolution+1441.pdf> accessed on 30/10/11
-  Ewan MacAskill & Julian Borger, Iraq war was illegal and breached UN charter, says Annan <http://www.guardian.co.uk/world/2004/sep/16/iraq.iraq>accessed on 1/11/11
-  Hugo Grotius, The Law of War and Peace, Bk II, Ch I, XVII (1625)
-  Henkin, The Reports of the Death of Article 2(4) are Greatly Exaggerated, 65 AJIL (1971) 544
-  Steve Crawshaw and Stephen Vines, Will China invade Taiwan?, The Independent, 9th February 1996, <http://www.independent.co.uk/news/uk/will-china-invade-taiwan-1318061.html> Accessed on 1st January 2012
-  US Military plan casts wry eye at China, CBS News, January 5th 2012 <http://www.cbsnews.com/8301-18563_162-57353412/u.s-military-plan-casts-wary-eye-at-china/> Accessed on 6th January 2012
-  Remarks by Alfred P. Rubin, panel on “Should the laws of war apply to terrorists?” The American Society of International Law, 1985, quoted at International Law of War Association <http://lawofwar.org/introduction.htm> Accessed on 4th January 2012