Former US attorney general Ramsey Clark has joined the team of Jordan-based lawyers defending Saddam Hussein.
Clark has helped numerous figures at odds with the US government
Mr Clark - who held office in the 1960s under President Lyndon Johnson - said his principal concern was protecting the rights of the former Iraqi leader.
Saddam Hussein this month saw a lawyer for the first time since his capture.
Left-wing activist Mr Clark described the special tribunal established to try members of the former regime as a creation of the US military occupation.
He said it had no authority in law as a criminal court.
Mr Clark is joining a panel of about 20 prominent Arab and non-Arab lawyers who have volunteered to defend the former Iraqi leader.
He is an outspoken critic of American foreign policy on Iraq and visited Saddam Hussein in Baghdad in February 2003 just before the US-led invasion.
After leaving office in 1969, he became active in the anti-Vietnam War movement. More recently, he has offered legal advice to numerous figures at odds with the US government including former Yugoslav president