I remember vividly the day the United Nations Security Council decided to refer the situation in Sudan’s Darfur to the International Criminal Court in March 2005. From my position as among the first judges to be elected to serve on the world’s young criminal court, it felt like history was in the making.

Fifteen years later, I see the recent decision from the government of Sudan to allow former President Omar al-Bashir to stand trial in front of the International Criminal Court as proof that the arc of history is long and bends towards justice.

In the end, the five counts of crimes against humanity, two counts of war crimes and three counts of genocide against al-Bashir outlived his 30 years of brutal rule, which ended last year as a result of the uprising of the Sudanese people.

This should serve as a reminder for perpetrators of serious abuses around the world that justice, although slow, will prevail, and that impunity for serious international crimes will be short-lived.

This message should chime particularly loudly for neighbouring South Sudan, where government and opposition leaders had until this week to implement a 2018 peace agreement supposed to end seven years of civil war laden with egregious abuses on all sides.

The conflict in the world’s youngest nation has claimed more than 400,000 lives since 2013. Abuses have been rampant. Human rights organisations have documented atrocities including the resurgence of mass rape as a weapon of war.

Yet while ordinary South Sudanese people suffered through this brutal conflict, elites on all sides continue to profiteer from the violence and chaos. They have used war as a cover to plunder natural resources in this oil-rich country, and have looted government money to fund lavish lifestyles, pay for illicit weapons and fund militia who commit horrific abuses against their own people.

Early February, a panel of African civil society leaders came together to shine a much-needed spotlight on some of the most brazen of those who have obstructed peace in South Sudan for their own gain by taking the unusual step, in Oscars week, of launching their own award ceremony, the “Spoilers of Peace Awards”.

Spoilers on all sides of the conflict were nominated, as well as international companies and governments, complicit in fuelling the conflict, including the Ugandan government and oil companies Petronas and Dar Petroleum.

The forthcoming ICC trial of al-Bashir must serve as a clear warning and lesson to those exposed as spoilers of peace and perpetrators of atrocities, in South Sudan, and around the world.

Omar al Bashir eschewed his chance to change his ways and uphold fundamental rights when he was still in power, and will rightly be brought to justice.

But it is not too late for the leaders of South Sudan to edit how the history books will write about their legacy. They must take urgent steps to fulfil the promises made to the people of South Sudan in the Revitalised Peace Agreement, including finding compromise on key outstanding issues, and taking a zero-tolerance approach to ongoing abuses — particularly the scourge of sexual violence.

Furthermore, if they seek to avoid the international community stepping in to deliver justice via the ICC, the hybrid court must be established without delay to ensure that perpetrators are held to account for their crimes.

When all is said and done, history will be a much harsher judge than the ICC. If found guilty, future generations will remember Omar al-Bashir for the crimes that led to his downfall.

Atrocities and prosecution will similarly define the legacy of South Sudanese leaders unless they change course and start using their power for the greater good of their people.

Navi Pillay is former UN high commissioner for human rights and president of the UN International Criminal Tribunal for Rwanda