The men are facing charges connected with the killings of 148 Shi'ites in 1982 in the town of Dujail.
The session began with chief judge Rauf Abdel Rahman reading a report by handwriting experts expected to verify the signatures of Saddam and other defendants on documents authorising the killings.
In the previous April 19 hearing, Judge Rahman ruled after seeing a report that signatures linking the ousted Iraqi leader to a massacre in the 1980s were "authentic".
If proved guilty, Saddam and the seven others face the death penalty.
Saddam has dismissed the evidence, insisting the documents were forged, and claimed the witnesses testifying against him have been bribed by the prosecution.
Meanwhile, a carbomb that exploded in central Baghdad has killed at least three people and wounded around 20.
The parked car exploded during morning rush hour on a major street near the Tigris River, close to Medical City, one of the capital's largest hospitals; a complex of government buildings; a bus station; and a busy traffic roundabout.
The blast in the Bag al-Muadim section of the capital destroyed at least three other cars and heavily damaged shops, blowing out their windows, said police 1st Sergeant Nabil Abdul-Latif.
He said at least three people were killed and 20 wounded. The injured included two policemen who were directing traffic.