After five years in U.S. custody, Iraqi former Deputy Prime Minister Tariq Aziz used a walking stick as he entered the courtroom to go on trial for the 1992 executions of 42 Baghdad merchants.
The trial's opening session was delayed nearly eight hours and lasted less than 45 minutes.
Chief Judge Raouf Abdul-Rahman adjourned the session until May 20.
He said one of the other defendants, Ali Hassan Al-Majid, was too ill to appear in court.
Majid became known as "Chemical Ali" for his role in the use of poison gas to kill Kurdish civilians. He has already been sentenced to death in a separate case, the killings of tens of thousands of Kurds in the Anfal campaign of the 1980s.
The U.S. military says he had a heart attack last month while on a hunger strike.
Aziz, Majid and six other men are on trial for the 1992 executions of 42 merchants who were accused of illegally raising food prices while Iraq was under U.N. economic sanctions. The businessmen were rounded up from one of Baghdad's wholesale markets and quickly executed after a brief trial. Aziz is accused of signing the execution order as a member of Saddam's Revolutionary Command Council, which rubber-stamped the Iraqi leader's decisions.
Lawyers for Aziz have said the charges against him are baseless and politically motivated.
To most of the world, Tariq Aziz was the public face of Saddam Hussein's regime. He was deputy prime minister before the U.S.-led invasion of Iraq, and had earlier served as foreign minister. He was the only Christian member of Saddam's inner circle. He surrendered to U.S. officials shortly after the fall of Baghdad in 2003. His relatives and lawyers say he is in poor health.