Former Iraqi leader Saddam Hussein has made an outspoken attack on the judicial process, before pleading not guilty at his trial in Baghdad.
He refused to confirm his identity, and questioned the validity of both the trial and the judge.
"Who are you? What does this court want?" Saddam Hussein asked the judge.
Saddam and seven associates, who all pleaded not guilty, are charged with ordering the killing of 143 Shia men in 1982 in Dujail.
The trial is being heard in an imposing marble building that once served as the National Command Headquarters of Saddam Hussein's Baath Party, in the heavily fortified Green Zone in the Iraqi capital.
TV pictures showed Saddam Hussein and his co-defendants being led into pens in the courtroom.
The 68-year-old former leader was wearing a dark suit with an open-necked shirt and carrying a copy of the Koran. The BBC's John Simpson in the court says he looked thinner and more sallow than in his last public appearance.
Asked to confirm his name by chief judge Rizgar Mohammed Amin, a Kurd, Saddam Hussein refused.
"Have you ever been a judge before?" Saddam said.
Amid some verbal sparring with the judge, the former Iraqi leader stated: "I preserve my constitutional rights as the president of Iraq. I do not recognise the body that has authorised you and I don't recognise this aggression. What is based on injustice is unjust ... I do not respond to this so-called court, with all due respect."
The trial is being presided over by five judges, with Mr Amin in overall charge. The identities of judges had been kept secret to ensure their safety, but Mr Amin's name was revealed by US officials just before the trial began.
A small number of observers and journalists are in the courtroom, but the public has been excluded.
The case is the first of many expected to be brought against the former Iraqi leader.
It concerns the rounding up and execution of 143 men in Dujail, a Shia village north of Baghdad, following an attempt there on Saddam Hussein's life. Court officials say the case was chosen because it was the easiest and quickest case to compile.
The charge carries the death penalty, though Saddam Hussein and his associates have the right to appeal if they are found guilty.
Prosecution lawyers are also expected to bring charges concerning the gassing of 5,000 people in the Kurdish village of Halabja in March 1988, and the suppression of a Shia revolt following the first Gulf War.
Human rights groups have expressed concerns about the trial as a Human Rights Watch report says the Iraqi Special Tribunal "runs the risk of violating international standards for fair trials".
Amnesty International has sent three delegates to Baghdad to ensure Saddam Hussein receives a fair trial, and to oppose the death penalty if he is found guilty.
Saddam Hussein was captured in 2003 after the American-led invasion of Iraq.
BBC News