Lawyers for Bemba said in the January hearing that members of his militia group accused of atrocities in the Central African Republic (CAR) were not under his command.
They argued before the court in The Hague that the men, deployed in 2002 to help put down a coup, were under the command of then-CAR president Ange Felix Patasse.
The court has given the defence until 24 April 2009 to respond, with an opportunity for alleged victims to make submissions first.
Bemba — a former DR Congo vice-president and presidential election loser in 2006 — held a dual role as president and commander-in-chief of his Movement for the Liberation of Congo.
The former role may not allow the prosecution sufficient leeway to establish criminal responsibility.
The MLC entered the Central African Republic in an unsuccessful bid to stave off a coup against Patasse.
ICC prosecutors allege they committed war crimes and crimes against humanity including rape, torture and murder while on Central African territory.
The 46-year-old Bemba, who fled DR Congo in April 2007, was arrested on 24 May 2008 by Belgian authorities and transferred to the ICC on 3 July.
The prosecution is seeking to hold Bemba criminally responsible for five counts of war crimes and three counts of crimes against humanity including rape, torture and murder, committed on the territory of Central African Republic from October 2002 to March 2003.
