South Africa’s Supreme Court on has rejected an appeal by the government against a ruling that the state made a mistake in letting Sudanese President Omar Hassan al-Bashir leave the country despite a court order barring him from doing so.

Al-Bashir was in South Africa last June for an Africa Union Summit, and the court issued an order barring him from leaving the country until the end of a hearing on whether he should be detained under a global arrest warrant. He was however allowed to fly back to Sudan.

The court said he should have been arrested to face genocide charges at the International criminal Court (ICC) because South Africa is a signatory of the international court, and therefore obliged to implement arrest warrants.

The ICC had issued an arrest warrant against al-Bashir on charges of masterminding genocide in Sudan’s Darfur region. Bashir however denies the charges.

The government had asked the court to overturn the ruling, with its lawyers arguing that a gazzette notice granted diplomatic immunity to all delegates at the summit.

In its ruling, the Supreme Court said the government’s failure to arrest Bashir “was inconsistent with South Africa’s obligations in terms of the Rome Statute…and unlawful”.