By Andrew Clapham, Professor of International Law.

There is no doubt that international law has outlawed the resort to war to settle disputes between states. International law tells us that, as a rule, the use of force by one state against another state has to be either authorised by the United Nations (UN) Security Council, or a necessary and proportionate measure of self-defence in response to an armed attack. Of course, these simple propositions become more complicated in the contemporary world. Is it correct to argue that states can use force against the forces of the so called “Islamic State” in Syria as a measure of collective self-defence of Iraq in response to an armed attack on Iraq by that same “Islamic State”? Is there room for an exception for humanitarian intervention when the Security Council is blocked and force can conceivably be used to avoid a humanitarian catastrophe? Does a leader who orders force to rescue nationals abroad commit the crime of aggression? Finding one's way through the competing arguments is the task of the international law student at the Graduate Institute — and to attempt to answer them here would not do justice to the complexity of the issues and would pre-empt the interesting debates I am looking forward to.

It is also uncontroversial that international humanitarian law prohibits certain behaviour in armed conflict. Not only are certain weapons, such as chemical weapons, prohibited, but so too is conduct such as targeting civilians or torturing one's prisoners. The lists of prohibitions remain uncontroversial for the most part. Where we have the greatest challenge is that in the contemporary world, in situations such as Syria, thousands of victims are being killed in violation of these norms and there is almost no accountability. States have moreover found themselves incapable of ending these violations.

Is international law part of the problem? Should the UN Charter make it easier for states to intervene to save lives? In this case I doubt that states are really hesitating because they feel constrained by international law. A new international obligation that demanded that states do more to halt violations of the laws of war would not generate the necessary political will to end the egregious violations or even the violence itself. The relatively recent idea of a “responsibility to protect” suggests that the international community of states and the UN itself have to strive to save people from ongoing war crimes, genocide and crimes against humanity. But the normative framework does not provide leaders with the imagination and commitment to do this, it just suggests that they must do something. We need more than law and lawyers to fix these problems.

A further role for international law is to provide a framework of international criminal law which facilitates the prosecution of war crimes and other international crimes at the national and international levels. Of course only a tiny handful of the international war criminals will be prosecuted. But everyone fighting in a contemporary conflict should be on notice that their past may one day catch up with them as a result of the opportunities for prosecution that are offered by international law. It was the Torture Convention that obliged the United Kingdom to detain Pinochet and deny him immunity years after his offences, while the customary laws of war led to the prosecution of those involved in the conflicts in the former Yugoslavia, Rwanda and Sierra Leone. Just last November, Alieu Kosiah, a former commander of the United Liberation Movement of Liberia for Democracy, a rebel group that fought against Charles Taylor, was detained in Switzerland where he is living and where he may now face prosecution for war crimes. Today the Prosecutor of the International Criminal Court is engaged in investigations in Uganda, Democratic Republic of the Congo, Central African Republic, Darfur (Sudan), Kenya, Libya, Côte d’Ivoire and Mali. There are preliminary investigations with regard to alleged crimes in Honduras, Afghanistan, South Korea, Ukraine and Iraq, and the Prosecutor is assessing if there are genuine national proceedings being carried out in Georgia, Guinea, Colombia and Nigeria. Most recently, in January 2015, the Prosecutor opened a preliminary examination into the situation in Palestine.

A final role for international law in armed conflict has, in recent months, become very contested. It is fairly clear that international law empowers states and individuals to do things which would otherwise be illegal under national law. The killing by a state's armed forces of a member of the armed forces of another state in times of armed conflict cannot be prosecuted as murder by the victim's state. The killer has what is called “combatant immunity”. In the same way, prisoners of war can be detained until the end of the conflict. There are no obligations to bring such detainees before a judge with a view to prosecution. International law provides the authority to kill, destroy property and detain without trial in circumstances where the law would normally suggest that such behaviour is illegal. But the situation becomes more complex when the enemy is a non-state actor. Can rebels and terrorists be detained without trial until the end of the war on terror? Can they be shot on sight? States are fairly clear that non-governmental opposition forces are not entitled to do these things. So what happened to the equal application of the laws of war to both sides?
International law is less codified in this area, and there is ongoing tension now with some suggesting that international human rights law should be taken into account. This would suggest that states have to justify their violence and detention. They would need to have a basis in law which entitles them to detain those they capture, and that basis should be reviewed by an independent authority. Some see the role of international law predominantly authorising states to do what they say they need to do. Others see the role of international law as limiting states’ margin for manoeuvre and demanding judicial oversight. These issues are currently being fought out in Geneva in fora such as the UN Human Rights Committee and the UN Human Rights Council, as well as in national and international courts. Watch this space.

This article was published in Globe, the Graduate Institute Review.