Why was Saddam prosecuted for Dujail and not the much bigger incidents, say at Halabja?
Dujail was the subject of the first trial because it was quite straightforward to prosecute. Saddam is also being tried for the 1988 Anfal operation in which 50,000 Kurds were killed, and a trial over the gassing of Kurds at Halabja is in preparation. Anfal occurred at the end of the Iran-Iraq war, in which Saddam had UK and US support.