As the threat of nuclear war becomes a closer reality, the legal status of nuclear weapons is more important than ever.
Albert Einstein famously said that if he’d foreseen Hiroshima and Nagasaki he would have torn up his formula in 1905.
The catastrophic bombings, which killed at least 129,000 people, remain the only instance where nuclear weapons have been used during war.
Even against the backdrop of a politically divided electorate, most people can agree that the consequences of nuclear war are devastating. However, the legal status of nuclear weapons is far more complicated. So what does the law say?
Nuclear Weapons and International Law
One of the most important instruments governing nuclear weapons is the 1977 Additional Protocol I to the Geneva Conventions. The Geneva Conventions, which are made up of four treaties and three additional protocols, set the standard for humanitarian treatment during war. Protocol I is relevant because it specifically prohibits weapons that “cause superfluous injury or unnecessary suffering” and types of warfare that “cause widespread, long-term, and severe damage to the natural environment.”
The Geneva Conventions also help make up International Humanitarian Law (IHL), which is different from Human Rights Law. IHL governs conduct during war, attempting to reduce the impact on civilians and regulate methods of combat. There’s an ongoing debate over how IHL is related to human rights law. Some observers argue that IHL should be understood as a subset of human rights, with both applying at all times. This perspective makes it more difficult to argue for the legality of nuclear weapons because of the wider scope of protections offered by human rights. Others see the two law regimes as completely separate, with human rights no longer applying once IHL is in place.
In either case, IHL can help assess the legality of nuclear attacks. Two of its most important provisions are the principles of distinction and proportionality. The principle of distinction is meant to protect civilians during war by preventing combatants from attacking non-military targets. The principle of proportionality is meant to make sure that warring parties use the minimum amount of force necessary to defeat the enemy. These core rules both make it very difficult for states to justify the use of nuclear weapons – but not, however, impossible.
What does the International Court of Justice say?
In 1996, the International Court of Justice (ICJ), the UN’s main judicial body, advised that using nuclear weapons would generally be contrary to the principles of IHL. However, the court didn’t definitively state that nuclear weapons were illegal. Instead, it concluded that the lawful use of nuclear weapons was still theoretically possible in “extreme circumstances of self-defence, in which the very survival of a State would be at stake”
The problem with this statement is that most wars are likely to be seen as “extreme” by participating countries. As a result, it’s still unclear in what exact circumstances the use of nuclear weapons could be deemed lawful.
Does that mean that nuclear weapons are legal?
It might be safer to say that nuclear weapons aren’t always illegal. There’s still no consensus on when a nuclear attack would be consistent with international law. Many countries, including the UK, still argue that, by acting as a deterrent, nuclear weapons are an important part of self-defence.
In the absence of clear position from the ICJ, it’s helpful to look at what other protections against nuclear war are in place. In addition to the 1968 Non-Proliferation Treaty, there’s also the Treaty on the Prohibition on the Prohibition of Nuclear Weapons, passed in July 2017 by more than 120 countries. However, none of the nine countries which are believed to have nuclear weapons, including the UK, supported the treaty. According to the UN Office for Disarmament Affairs, there are still roughly 22,000 nuclear weapons in the world today.
So there’s no comprehensive or universal ban on nuclear weapons. But if there’s any lesson to be learnt from Hiroshima, it’s that nuclear war should never reoccur, regardless of its legality.