Ethnic violence in the Ituri region between the Hema and Lendu, as well as clashes between militia groups vying for control of mines and taxation, has killed up to 60,000 people since 1999.
A decision to confirm charges against Lubanga and launch a trial would be a landmark for the ICC, set up as the first permanent global war crimes court in 2002.
However, the court could throw out the charges, request further evidence and investigations, or ask prosecutors to consider amending a charge.
Lubanga's lawyer has accused the prosecution of withholding information he needs to prepare a defence.
Meanwhile, some victims' groups want the charges against Lubanga to be expanded to include crimes such as killings, rape and torture.
A decision to go ahead with the trial is a litmus test for the ICC, following the United States' refusal to support the full extent of the court's powers.
The Bush administration has been notably hostile to the ICC, in regard to any prospect of the court exercising its jurisdiction to direct investigations and prosecutions against US military and political personnel.
DR Congo was the battleground for rebels, local factions, tribes and several neighbouring countries in a 1998-2003 war.
Four million people died, mainly from hunger and disease, during the conflict.
Up to 30,000 children were associated with Congo's armed groups during the height of the war, according to estimates.
Lubanga is the only suspect to be delivered so far to the court that issued its first arrest warrants in 2005 for leaders of the Ugandan Lord's Resistance Army (LRA).
The LRA led a 20-year insurgency that killed tens of thousands of people.
Luis Moreno-Ocampo, the ICC's chief prosecutor, also plans to charge suspects soon for atrocities in Sudan's Darfur region, which the UN Security Council asked him to investigate in 2005.