Last night on our show, Luis Moreno-Ocampo, the prosecutor for the International Criminal Court in The Hague, talked about some of the challenges faced by those seeking justice for crimes against humanity.

When it comes to enforcing international law, one of the biggest difficulties is to actually convince sovereign governments to turn over those wanted by the court. Even when an international warrant is issued, it cannot be applied unless local authorities are willing to carry out the arrest and send the accused to the court.

Sudanese President Omar al-Bashir has provided one of the most prominent examples of how easy it can be to evade international justice: The first head of state to be indicted by the ICC, he was accused by Moreno-Ocampo in 2008 of genocide, war crimes and crimes against humanity for his role in the Darfur conflict, in which forces loyal to Bashir's government in Khartoum used mass killing, rape and displacement to drive people from their homes in the western region of Sudan.

The ICC issued a warrant for his arrest in 2009, but Sudanese authorities so far refuse to turn their leader over to the court; neither will Sudan's allies in Africa, meaning that so long as Bashir only travels to friendly states, he can avoid prosecution.

Until this week, one of the countries Bashir felt free to visit was Kenya. In fact, the president visited his former neighbour (the two countries are now separated by South Sudan) last August, with no incident. Kenya is a signatory to the ICC, but it's also a member of the African Union, which has asked its members not to enforce the warrant.

Once Bashir left, however, the Kenyan chapter of the International Commission of Jurists, an NGO of legal professionals, filed a legal suit to ensure that his next visit would result in his being arrested and turned over to the ICC.

On Monday, the High Court in Nairobi issued a warrant for Bashir's arrest. In retaliation, the Sudanese government announced yesterday it will expel Kenya's ambassador to Khartoum.

Although the Kenyan government has said it will appeal the ruling, the judge's ruling is a clear vote in favour of international law - something Kenya already knows about: Moreno-Ocampo himself was part of an ICC investigation to find those responsible for the eruption of violence that followed Kenya's elections in 2007.

"If the government does not execute this court warrant, it will not only be failing in its obligations as set out in the Rome Statute but also putting unnecessary and undue strain on the already bruised human rights records of the country after post-election violence serious crimes," said Mwaura Nderi of the ICJ yesterday.

Here is a report from Kenyan TV on the court's ruling: