Jordan has on Monday defended its decision not to arrest Sudanese president Omar al-Bashir during an Arab League summit last year, saying it was not obliged to detain and hand him over to the International Criminal Court.
Amman's lawyers are appealing a December 2017 decision by the court which found that Jordan "failed to comply with its obligations" when it refused to detain Bashir, wanted by the Hague-based tribunal for genocide, war crimes and crimes against humanity.
The ICC's judges also referred the incident to the United Nations Security Council and the court's Assembly of States Parties, which represents the nations that have ratified the ICC.
Long-time Sudanese leader Bashir jetted into Jordan in March last year to attend an annual Arab League summit, despite opposition from human rights groups and two ICC warrants out for his arrest.
But on Monday Amman's representative Mahmoud Daifallah Mahmoud Hmoud said the ICC's "pre-trial chamber erred in its conclusions".
Jordan "regards Omar al-Bashir as a sitting head of state and therefore immune to arrest", based on the international legal principle of comity between states.
"Jordan fully subscribes to the importance of the fight against impunity and the need to punish those responsible for crimes within the jurisdiction of the court," he said. "However, this cannot be done at the expense of fundamental rules and principles of international law aimed at securing peaceful relations among states," he said.
Judges will during the next five days listen to complex legal arguments which touches a crucial aspect of the ICC's work, namely whether a head of state can indeed be arrested and handed over to the ICC, set up in 2002 to try the world's worst crimes.
The appeals judges can then either uphold the court's earlier decision to sanction Jordan, or to scrap the measures.
Meanwhile Bashir continues to travel with impunity including to Morocco and Rwanda last year. He has steadfastly denied the charges.
Last year, the ICC's judges ruled that South Africa too flouted its duties to arrest Bashir during a 2015 visit, but they declined to refer the matter to the UN Security Council.
Bashir faces 10 charges, including three of genocide as well as war crimes and crimes against humanity and charges relating to the conflict in the western Darfur region.