In the six years since the outbreak of rebellion in Darfur, the Sudanese army and its militia allies have committed war crimes on a horrific scale. They have used rape systematically to dehumanise women from ethnic groups associated with the revolt. They have burnt thousands of villages, killed tens if not hundreds of thousands of people and driven millions from their homes.

By issuing an arrest warrant for Omar al-Bashir, who has presided over the carnage, the International Criminal Court has sent a robust signal to would-be war criminals throughout Africa and the wider world. This is the first time the court has indicted a sitting head of state. As such it shows that no office, however high, is beyond the reach of international law. Not surprisingly, human rights activists are celebrating what they hope is a seismic shift towards ending the impunity of war criminals.