Following the 1991 Gulf War, in which a U.S.-led alliance drove Iraqi forces out of Kuwait, Shi'a in southern and central Iraq rose up against Hussein's regime. Iraqi forces crushed the uprising, killing tens of thousands of Shi'a.
The 15 military and government officials on trial for crimes against humanity include Hussein's cousin, Ali Hassan al-Majid, who is known as "Chemical Ali" for ordering gas attacks against Iraqi Kurds.
In his opening statement, the chief prosecutor accused al-Majid of carrying out cold-blooded executions of Shi'a during the crackdown on the uprising.
The prosecutor accused al-Majid of visiting detention centers, tying the hands of detainees, and shooting them dead.
Al-Majid and two of the other defendants have already been sentenced to death in a previous trial for genocide and crimes against humanity. Al-Majid was sentenced to hang for genocide against the Kurds in a 1980s campaign that killed tens of thousands, and is awaiting the result of an appeal.