Lawyers representing the South African government are at the International Criminal Court (ICC) to answer questions about the country's failure to arrest the Sudanese president, Omar al-Bashir.
The court in The Hague is considering whether South Africa ignored the ICC's rules when it allowed Mr Bashir to attend an African Union gathering in Johannesburg two years ago.
The Sudanese leader has been charged with war crimes and crimes against humanity in Darfur.
South Africa denies that it broke international law by its actions.
If found to be non-compliant, South Africa could be referred to the UN Security Council, which has the power to impose sanctions.