Hissène Habré was the President of Chad from 1982 to 1990. He was sentenced to life imprisonment in Senegal on Monday (30 May) for crimes against humanity committed during his brutal reign, including sexual slavery, rape and ordering the killing of up to 40,000 people and torture of many thousands more.

This was a momentous verdict in many ways. It was the first time the African Union had supported the establishment of a special criminal court (like the UN-supported courts in the former Yugoslavia and Cambodia), and also the first time any country had exercised the universal jurisdiction which attaches to crimes against humanity to convict a former head of state of another country. The New York Times called Habré’s trial a ‘milestone for justice in Africa.’ I will return to the significance of the trial after a look at its convoluted history.

Under the Convention Against Torture (CAT), States are obliged either to prosecute perpetrators found in their jurisdiction, or to extradite them to a State which will prosecute that person (also known as the international obligation to fight impunity, or aut dedere aut judicare). Habré fled to Senegal after being forced out of Chad in a 1990 coup, so the obligation was on that nation’s government to act.

Habré was indicted in 2000, but Senegalese appellate courts ruled that he could not be tried in that country for want of jurisdiction under domestic law. In response in 2001, Souleymane Guengueng and other victims took a case against Senegal to the UN Committee Against Torture, which found in 2006 that Senegal was in breach of the Convention for failing to fulfil its obligation to prosecute or extradite Habré within a ‘reasonable time frame.’

Meanwhile, the campaign for justice proceeded on other fronts. The Chadian Government was persuaded to formally waive Habré’s head of state immunity in 2002. In 2005, other victims (some of whom were Belgian citizens) filed a case in Belgium calling for Habré’s extradition to face prosecution. This became (in 2009) a suit between Belgium and Senegal in the International Court of Justice (ICJ), which in 2012 ordered Senegal ‘without further delay,’ to ‘submit the case of Mr. Hissène Habré to its competent authorities for the purpose of prosecution, if it does not extradite him.’

After the Belgian filing, but before the ICJ suit, Senegal consulted the African Union on the best approach. The Union set up a Committee of Eminent African Jurists which recommended Habré be tried in Senegal ‘on behalf of Africa.’ Senegal amended its domestic legislation to extend its jurisdiction to the relevant crimes in 2007, but continued to delay the actual trial. After the ICJ ruling in 2012, agreement with the African Union was expedited and, after 16 years of lobbying from victims and rights campaigners, the Extraordinary African Chambers (Chambres africaines extraordinaires) were established under a statute similar to those of international criminal courts to try Habré.

The trial began in July 2015 and concluded in February this year. It heard from 93 witnesses who told horrific stories of summary executions, torture and other crimes against members of the Hadjerai and Zaghawa ethnic groups, people from southern Chad and political dissidents. Even among this litany of misery, stories of rape and mistreatment from women including Khadidja Hassan Zidane stood out, and eventually led to rape and sexual slavery being added to Habré’s charge sheet. This was another important aspect of the trial, because crimes against women have historically been underrepresented (or even overlooked) in international criminal prosecutions, and there are still many obstacles to investigating and prosecuting perpetrators of such crimes.

This testimony, along with evidence gathered by the Chambers itself and from previous Belgian and Chadian investigations, led to this week’s guilty verdict. They also led to prosecutions in Chad of Habré-era police officers in 2015. For his part, Habré refused to cooperate with what he claimed was an illegitimate court, so Senegalese lawyers were appointed to mount his defence. This is a familiar phenomenon from other former rulers facing criminal charges relating to their time in power. Despite his continued refusal to engage with the process, Habré’s defence team has indicated their intention to appeal; they have until 10 June to do so.

Another notable development on Monday was the US Secretary of State John Kerry’s official response to Habré’s conviction. Kerry welcomed the outcome, calling it a ‘landmark in the global fight against impunity for atrocities.’ However, he went on to state:

As a country committed to the respect for human rights and the pursuit of justice, this is also an opportunity for the United States to reflect on, and learn from, our own connection with past events in Chad.

This statement alludes to US support for Habré in the 1980s, when he was at war with Libya’s Muammar Gaddafi. This war was the other prominent feature of Habré’s rule, and indeed his lawyers argued it was the defining one, portraying him as a hero who prevented Chad from becoming a Libyan province. However, it is now acknowledged that US support (in the form of money and weapons) enabled Habré to commit atrocities against his own people, as well as wage war.

The final word on the trial’s significance goes to Human Rights Watch lawyer Reed Brody, whose work on bringing Habré and others to trial has earned him the enviable sobriquet ‘The Dictator Hunter.’ He issued an official statement on Twitter:

Habré’s conviction for these horrific crimes after 25 years is a huge victory for his Chadian victims, without whose tenacity this trial would never have happened. This verdict sends a powerful message that the days when tyrants could brutalize their people, pillage their treasury and escape abroad to a life of luxury are coming to an end. Today will be carved into history as the day that a band of unrelenting survivors brought their dictator to justice.

Against a long history of impunity for dictators and war criminals, the Habré ruling is a demonstration that the fight for justice can be long and difficult, but is ultimately worth the struggle. It should be welcomed and celebrated as a major step towards the establishment of the international rule of law.