Wael Ghonim, an icon of the anti-Mubarak uprising, rejected Morsi's decisions, arguing the president could have protected the revolution without concentrating so much power in his hands.
"The revolution was not staged in search for a benign dictator, there is a difference between revolutionary decisions and dictatorial decisions. God is the only one whose decisions are not questioned."
The Egyptian leader decreed that all decisions he has made since taking office in June and until a new constitution is adopted and a new parliament is elected cannot be appealed in court or by any other authority. Parliamentary elections are not likely before next spring.
The decree also barred the courts from dissolving the controversy-plagued assembly writing the new constitution. Several courts have been looking into lawsuits demanding the panel be disbanded.
The Brotherhood and Morsi allies who dominate the assembly have pushed to give the draft an Islamist slant that opponents fear would marginalize women and minority Christians, infringe on personal liberties and even give Muslim clerics a say in lawmaking. Liberal and Christian members withdrew from the assembly during the past week to protest what they say is the hijacking of the process by Morsi's allies.
Morsi on Thursday extended by two months, until February, the deadline for the assembly to produce a draft, apparently to give members more time to iron out their differences.
He also barred any court from dissolving the Islamist-led upper house of parliament, a largely toothless body that has also faced court cases.
The president made most of the changes Thursday in a declaration amending an interim constitution that has been in effect since shortly after Mubarak's fall and has over time become a ramshackle patchwork. The military, which took power after Mubarak, set the precedent for the executive unilaterally issuing constitutional changes, which it did several times during its 16-month rule.
The moves come as Morsi basks in lavish praise from President Barack Obama and Secretary of State Hillary Rodham Clinton for mediating an end to eight days of fighting between Israel and Gaza's Hamas rulers. Clinton was in Cairo on Wednesday, when she held extensive talks with Morsi.
Morsi not only holds executive power, he also has legislative authority after a previous court ruling just before he took office on June 30 dissolved the powerful lower house of parliament, which was led by the Brotherhood. With two branches of power in his hands, Morsi effectively took away many prerogatives of the third, the judiciary.
The provision for a retrial of Mubarak appeared to be a gesture to public opinion. The decree called for "new investigations and trials" against those who held "political or executive" positions in the old regime and who are accused of killing protesters.
Mubarak was convicted in June to life in prison for failing to stop the killing of protesters during last year's uprising against his rule, but many Egyptians were angered that he wasn't convicted of actually ordering the crackdown and that his security chief, Habib el-Adly, was not sentenced to death. Several top police commanders were acquitted, and Mubarak and his sons were found not guilty of corruption charges.
But the decree would not mean retrials for the dozens of lower-level police officers who have been acquitted or received suspended sentences in trials for killing protesters -- verdicts that have outraged many Egyptians. That exclusion will guarantee Morsi the loyalty of the powerful but hated police force.
Morsi on Thursday also fired the country's top prosecutor, Abdel-Maguid Mahmoud. A Mubarak-era appointee, Mahmoud has faced widespread accusations that his office did a shoddy job collecting evidence against Mubarak, el-Adly and the police in trials.
Morsi first fired Mahmoud in October but had to rescind his decision when he found that the powers of his office do not empower him to do so. So on Thursday, he decreed that the prosecutor general could serve in office only for four years, with immediate effect on Mahmoud, who had held the post since 2006. Morsi replaced Mahmoud with Talaat Abdullah, a career judge, and swiftly swore him in.
Thursday's decisions were read on state television by Morsi's spokesman, Yasser Ali. In a throwback to the days of the authoritarian Mubarak and his predecessors Anwar Sadat and Gamal Abdel-Nasser, the television followed up with a slew of nationalist songs.