Ziad Khasawna said on Wednesday that Clark, who held the office of attorney-general under US president Lyndon Johnson, had "honoured and inspired" the legal team by agreeing to help defend Saddam.
The former top US justice official, who arrived on Tuesday in Jordan where the defence team is based, has become known as a left-wing lawyer and firm critic of US foreign policy since leaving office.
He visited the ousted leader in Baghdad in February 2003 just before the US-lead invasion and has also been involved with the defence of former Yugoslav leader Slobodan Milosevic, on trial for war crimes at a UN court in The Hague.
Clark said in the Jordanian capital Amman that his principle concern was protecting the former president's rights, who only saw a lawyer for the first time this month - a year after his capture.
"In international law, anyone accused of crime has the right to be tried by a confident, independent and impartial court, and there can be no fair trail without those qualities," he said.
"The special court in Iraq was created by the Iraqi governing council, which is nothing more than a creation of the US military occupation and has no authority in law as a criminal court," he said.
The Iraq Special Tribunal was established by the US-led administration in Iraq last December to try members of the former government.
Clark also said the US itself must be tried for the November assault on Falluja, destruction of houses, torture in prisons and its role in the deaths of thousands of Iraqis in the war.