War crimes judges will rule Thursday if South Africa flouted international law by failing to arrest Sudan's President Omar al-Bashir, wanted for trial on charges of genocide in Darfur.

Legal experts widely expect that judges at the International Criminal Court will find that Pretoria, one of the founding members of the tribunal, failed to co-operate with the ICC based in The Hague.

And while the landmark decision will be aimed at sending a message to signatories of the court's founding Rome Statute that they must cooperate, many believe little concrete action will follow.

Despite two international arrest warrants issued in 2009 and 2010, Bashir remains at large and in office as conflict continues to rage in the western Sudanese region of Darfur.

In 2015, he attended an African Union summit in Johannesburg, and despite earlier consultations between ICC and South African officials then flew out of the country again unhindered.

The UN Security Council asked the ICC in 2005 to probe the crimes in Darfur, where at least 300,000 people have been killed and 2.5 million displaced since ethnic minorities took up arms against Bashir's Arab-dominated government in 2003, according to UN figures.

- 'Diplomatic immunity' -

Pretoria's lawyers argued at an April hearing at the ICC there "was no duty under international law on South Africa to arrest" Bashir.

Pretoria had sought legal clarification from ICC judges shortly before the visit, and argued there was "nothing at all" in the UN resolution to waive his diplomatic immunity.

But ICC prosecutor Julian Nicholls shot back that South Africa "had the ability to arrest and surrender him and it chose not to do so."

In the end, the only reason Pretoria did not arrest him was that South Africa "disagreed with ... the law as set out... so it did not comply," he said.

Bashir, who has been president of Sudan since 1993, has denied all 10 charges against him, including three of genocide and two of war crimes.

And he continues to travel, with Khartoum announcing Monday he will visit Moscow for the first time in August.

The ICC does not have its own police or enforcement body and relies on other countries to arrest or surrender suspects.

And while 124 nations have signed the Rome Statute which underpins the court, it has struggled to shore up its legitimacy at times, faced last year with unprecedented withdrawals and tainted by accusations of bias for focusing too heavily on war crimes in Africa.

"The ruling is... fundamental for future compliance," Carsten Stahn, international criminal law professor at Leiden University, told AFP.

A decision against South Africa "would send an important message that states cannot negotiate (their) legal obligations with the court," he said.

- 'Minimal' effect -

However, even if the court finds against Pretoria it has few practical sanctions to offer. And a defiant South African President Jacob Zuma has reiterated threats to pull out of the ICC.

The judges could refer the case to the court's Assembly of States Parties -- the body representing all the member nations -- or the UN Security Council for further action.

But Kaajal Ramjathan-Keogh, executive director at the Southern Africa Litigation Centre, cautioned that any effect, "looking at the ICC's history, is going to be minimal".

"Neither the ASP or the Security Council have taken any strict measures against countries that have failed to cooperate. I can't see that in this instance they will take a different approach," she said.

Source: AFP