The six defendants include Saddam Hussein's cousin Ali Hassan al-Majeed, known as "Chemical Ali." Majeed has been accused of genocide and faces the death penalty.
In Sunday's court session, Majeed said he was responsible for ordering the destruction of Kurdish villages and the relocation of villagers during the 1988 Anfal campaign. Prosecutors say 180,000 Kurds were killed during the campaign.
Majeed said he would not apologize and did not make any mistakes in ordering the villages cleared.
In a previous session, the prosecutor introduced documents showing that Saddam and his co-defendants were involved in planning chemical attacks against the Kurds.
The defendants say the Anfal campaign was a legitimate operation against Kurdish militants who sided with Iran during the 1980s Iran - Iraq war.
Saddam Hussein was executed at the end of December for his role in an earlier operation against Shi'ites from the village of Dujail. 148 men and boys from the town were executed after a 1982 assassination attempt against the former dictator.
Since Saddam's execution, Majeed has been sitting in the court chair that Saddam used to occupy. Some information for this report was provided by AFP and Reuters.