A quiet revolution for international justice just occurred, but the world hardly noticed. On December 15, the 123 countries that are members of the International Criminal Court (ICC) agreed that the court would begin to exercise jurisdiction over the crime of aggression beginning in July 2018.
As a result, for the first time in 70 years, an international court will have the ability to prosecute political and military leaders of countries that wage aggressive war. The crime of aggression will join war crimes, crimes against humanity, and genocide as crimes within the jurisdiction of the ICC.
Wars of aggression have been illegal since the 1928 Kellogg-Briand Pact and are prohibited by the United nations Charter.
Individual responsibility for the crime was first applied after World War 2 using what was referred to at the time as ''crimes against peace''. At the Nuremberg trials, 12 Nazi leaders were convicted of the crime and 22 imperial Japanese leaders were convicted at the subsequent Tokyo trials.
Since the closure of the Tokyo tribunal in 1948, no international court has held jurisdiction over the crime of aggression.
When the Rome Statute - the treaty establishing the ICC - was negotiated in 1998, the crime of aggression was left out of the court's jurisdiction, largely because of objections from the United States and Russia and the difficulty in reaching a consensus definition of the crime.
However, provision was made in the treaty for its inclusion if a diplomatic consensus could be reached. In 2010, the member states of the ICC reached such a consensus, defined the crime, and provisionally added the crime of aggression to the jurisdiction of the court.
However, the amendments were made conditional on them being accepted by at least 30 countries, and the earliest date the crime of aggression could be activated was set at January 1, 2017. The threshold of 30 accepting states was reached last year, and there are now 35 countries that have accepted the amendments.
Behaviour prohibited by the crime of aggression includes the planning or execution of an armed invasion, bombardment, a maritime blockade, or a military occupation of one sovereign country by another.
A central weakness of the adopted scheme is that the ICC will not have universal jurisdiction over all future incidents of aggressive war. The most likely route will be through the UN Security Council, which will be empowered to refer crime of aggression cases to the court for prosecution.
However, such references will be subject to the veto power of the permanent five members of the council: China, France, Russia, the United Kingdom, and the United States. Sceptics have pointed out that these five states are among those most likely to commit the crime of aggression, and that they will not allow their own nationals to be referred for prosecution.
Many have argued that the 2003 US-led invasion of Iraq and Russia's recent involvement in Ukraine amount to precisely the kind of behaviour encompassed by the crime of aggression.
Another route to the ICC is possible, but it requires the aggressor state to be an ICC member and to have accepted the amendments on the crime of aggression. The same sceptics have pointed to the obvious flaw: a state that accepts the amendments is unlikely to be the type of state that will have a political or military leader who will commit the crime of aggression.
However, it is encouraging that some states that have waged aggressive wars in the past, including Germany and Argentina, have accepted the amendments. Meanwhile, China, Russia, and the United States continue to refuse to join the ICC at all.
Although New Zealand is a member of the ICC, after the crime of aggression amendments were adopted in 2010, the National-led government refused to accept them, stating that it was adopting a ''wait and see'' approach as to whether the ICC could manage wielding jurisdiction over the crime of aggression.
For a peace-loving country that fought so hard for its seat on the Security Council in 2015-16, the delay has been a missed opportunity to play a role in global leadership. The new Parliament should seize this opportunity to indicate its commitment to world peace and justice by immediately ratifying the crime of aggression amendments to the Rome Statute so that New Zealand may be among the accepting states when jurisdiction over the crime of aggression is formally activated in July.
In the ongoing quest to eliminate wars of aggression, there is no plan B.
Stephen Smith is a senior lecturer at the University of Otago Faculty of Law.
