Bemba is charged with three counts of war crimes and two counts of crimes against humanity for the alleged atrocities in Central African Republic (CAR).
"To my knowledge it’s certainly the first significant case where large numbers of rapes are alleged to have taken place and where the leader is being held responsible for them, even though there’s no evidence that he himself committed a rape or even that he ordered them,” said William Schabas, professor of human rights law at the National University of Ireland, Galway.
"He’s being prosecuted for failing to prevent his troops from doing this.”
Some African leaders have claimed that their continent has been unfairly singled out, as the court has not assessed similar cases in other parts of the world.
“I think one of the reasons is that it’s politically, so far, proved easier for the prosecutor and his staff to work within Africa,” said Schabas.
“They don’t threaten big strategic interests of major powers in the way they might if they were pursuing cases in some of the other areas that have been put on the agenda at the court like Afghanistan, Gaza, Columbia and so on,” said Schabas.
Bembais pleading not guilty, and his lawyers argue that while the atrocities did take place, he was not in control of the troops who committed the offences.
The son of a privileged Congolese family, Bemba became wealthy in DRC through his involvement in the mobile phone industry.
When former dictator Mobutu Sese Seko was overthrown in 1997, Bemba created the Congolese Liberation Movement (MLC), with the help of the Ugandan President Yomeri Museveni.
Bemba's troops seized large areas of eastern Congo during the civil war that devastated the country from 1998 to 2003.
In 2002, former CAR vice president Ange-Ferlix Patasse called on Bemba and his MLC forces to help put down a coup attempt by Patasee's former chief of staff.
It's in that context that Bemba troops allegedly carried out horrific crimes including mass rape, killings and looting.
In 2003, Bemba negotiated a power-sharing deal with current president Joseph Kabila to become the country's vice-president.
Then, in 2007, Bemba fled the DRC after his soldiers clashed with Kabila's guard.
He was arrested on charges of war crimes on a visit to Brussels in May 2008.