"From tomorrow, any day could be the day" Saddam is sent to the gallows, the chief judge said.
The ruling could stoke Iraq's sectarian rage, with the Shiite majority demanding Saddam's death and most in the formerly dominant Sunni Arab community calling the trial tainted.
The decision came on a particularly bloody day in Baghdad, where at least 54 Iraqis died in bombings and police discovered 49 apparent victims of sectarian reprisal killings. Separately, the U.S. military announced the deaths of seven American soldiers.
In upholding the Saddam sentence imposed Nov. 5, the Supreme Court of Appeals also affirmed death sentences for two of his co-defendants, including his half brother. And it said life imprisonment for a third was too lenient and demanded he be given the death penalty, too.
Saddam's hanging "must be implemented within 30 days," said Aref Shahin, chief judge of the appeals court. "From tomorrow, any day could be the day of implementation."
Even Saddam's lawyers admit it's over, reports CBS News correspondent Randall Pinkston.
"The only other one we can appeal to is God," said Isam al-Ghazzawi, Saddam's defense attorney.
The White House called the ruling a milestone in Iraq's efforts "to replace the rule of a tyrant with the rule of law."
"Saddam Hussein has received due process and legal rights that he denied the Iraqi people for so long. So this is an important day for the Iraqi people," said deputy White House press secretary Scott Stanzel, who was aboard Air Force One flying from Washington to Waco, Texas.
Some international legal observers, however, contended Saddam's trial was unfair because of alleged interference by the Shiite-dominated government.
The ruling raised doubts about whether other victims of Saddam's ruthless rule — including families of Kurds who were gassed during a military operation in northern Iraq 20 years ago — will ever testify in court about their suffering.
But the announcement delighted Shiites, who endured persecution under Saddam, and who seek to remove a symbol of the old regime as U.S. and Iraqi forces battle a still-strong insurgency dominated by Sunni Arabs.
"We were looking forward to this day so as to achieve justice, though it comes late," said Ali al-Adeeb, a Shiite lawmaker. "The government should speed up implementing the verdict in order not to give any chance to the terrorists."
Under Iraqi law, the appeals court decision must be ratified by President Jalal Talabani and Iraq's two vice presidents. One of the two deputies is, like Saddam, a Sunni Arab.
Talabani, a Kurd, has voiced opposition to the death penalty but he previously deputized Vice President Adil Abdul-Mahdi, a Shiite Muslim, to sign execution orders on his behalf — a substitute legally accepted. Abdul-Mahdi has said he would sign a death warrant for Saddam.
The Sunni vice president, Tariq Al-Hashimi, reportedly gave his word that he also would sign a Saddam death warrant as part of the deal that gave him the job last April 22, witnesses at that meeting told The Associated Press in October.
Raed Juhi, a spokesman for the High Tribunal court that convicted Saddam, said the judicial system would ensure Saddam is executed even if the presidency does not ratify the decision.
"We'll implement the verdict by the power of the law," Juhi said.
He did not elaborate. It was unclear whether his comment indicated the potential for conflict between the presidency and other branches of government over the Saddam case.
Saddam is being held at Camp Cropper, an American military prison close to Baghdad's airport. It was unclear whether the hanging will take place there or perhaps at a Baghdad prison where the new Iraqi government has carried out other executions. Also unclear is whether the public or press will be allowed to witness the hanging or if will be announced only afterward.
Human Rights Watch, an international rights group, said figures in the U.S.-backed Iraqi government had undermined the credibility of Saddam's trial with public criticism of a judge early in the case that led to his resignation, along with other "political interference."
"Imposing the death penalty, which is indefensible in any case, is especially wrong after the unfair proceedings of the Dujail trial," said Richard Dicker, director of the group's International Justice Program.
As an example of Iraqi government interference, Dicker noted Mouwafak al-Rubaie, Iraq's national security adviser, announced the decision of the appeals court before the court itself. Al-Rubaie told AP of the decision about an hour before the chief judge announced it.
Shiite residents of Baghdad were delighted.
"We are very happy," said Riyah Abdul Sattar in Sadr City, a neighborhood where Shiite militias are strong. "We will get rid of him for sure."
The mood was different in Tikrit, a mostly Sunni Arab city north of Baghdad that lies near Saddam's hometown of Ouja.
"It is a political verdict that has no relation to law or justice," said Saad Ibrahim Khelil. "I do believe it's a kind of pressure against the (Sunni-led) resistance."
And in Amman, one of his defense lawyers said the execution of Saddam will be like opening the gates of hell, Pinkston reports.
"I think it will be a full scale war against Americans and all the occupiers, all the nationalities, whether British, English, American," said Isam al-Ghazzawi. "There will be blood. The ones who will be hurt most will be the Iraqi people."
But according to CBS News Middle East Consultant Fouad Ajami, "I think we really have to remember that this was an Iraqi trial and Saddam Hussein was basically tried by his own people... The Iraqi people got to see this man who dominated their lives being brought to justice... The sentence is going to be carried out, and it's really something that the Iraqi people have done for themselves. They want justice from this man, and they've gotten justice."
The appeals court also upheld death sentences for Barzan Ibrahim, Saddam's half brother and intelligence chief during the Dujail killings, and Awad Hamed al-Bandar, head of Iraq's Revolutionary Court, which issued the death sentences against the Dujail residents.
The court concluded the sentence of life imprisonment given to former vice president Taha Yassin Ramadan was too lenient and returned his file to the High Tribunal. Ramadan was convicted of premeditated murder.
"We demand that he be sentenced to death," said Shahin, the chief appeals judge.
At his trial, Saddam argued that the Dujail residents who were killed had been convicted in a legitimate Iraqi court for trying to assassinate him.
The televised trial was watched throughout Iraq and the Middle East as much for theater as for substance. Saddam was ejected from the courtroom repeatedly for political harangues, and his half brother once showed up in long underwear and sat with his back to the judges. Three defense lawyers and a witness were murdered during the course of its 39 sessions.
Saddam is in a second trial charging him with genocide and other crimes during a 1987-88 military crackdown on Kurds in northern Iraq. An estimated 180,000 Kurds died during the operation. That trial was adjourned until Jan. 8.
Saddam was captured while hiding with an unfired pistol in a hole in the ground near his home village north of Baghdad in December 2003, eight months after he fled the capital ahead of advancing American troops.