Fresh from a week in which he was declared the chief beneficiary of Israel's eight-day war in Gaza, Egypt's President Mohamed Morsi lost no time in turning his replenished guns on foes closer to home. Some of the elements of the decree he issued on Thursday were popular, even among those revolutionary groups who have bitterly opposed him on other issues. Sacking the prosecutor general, Abdel-Meguid Mahmoud, a Mubarak-era hatchet man whose blatantly tainted actions resulted in cases collapsing against attackers of demonstrators, is one. Offering cash to the victims of military and security forces' brutality and retrials was another.

But the decision to give all his decisions immunity from appeal up until the time a new constitution is enacted and fresh parliamentary elections are held next year is in a different league. He now wields total power. And therein lies a pyramid-sized contradiction. How can you enact a transition to democracy, instil respect for the rule of law and separate the powers of the judiciary, legislative and executive, by overriding all three? He says he has done it temporarily and unwillingly, when all other options have failed, but the fact remains that he has done it. Thus Transparency International called on Mr Morsi to rethink, arguing that he needs an independent judiciary to fight against corruption and uphold the law.

The president's supporters use three arguments in reply. None are without weight. First, the judiciary is not independent. Some of the judges, drawn from a movement formed to resist the old regime's antics – from which Morsi's vice-president, his minister of justice and the new prosecutor general are chosen – support his move. But others fight tooth and nail to impede the transition's path by mounting one obstacle after another. Would anyone seriously want the old military council to come back to life? And yet this too is on the constitutional court's agenda. If this court is the last bastion of the old regime's attempts to undo the revolution, what other choice does he face? Second, this court has already overturned one attempt he made to reinstate the parliament. Third, if he succeeds in pushing a new constitution through, it will halve his power, as Egypt will become a democracy in which an elected prime minister and president will hold equal sway. This, they argue, is hardly the action of a new pharaoh.

These arguments are political, and the politics of this were not looking too healthy on Friday as rival liberal and Islamist camps clashed in Cairo, Suez and Port Said. No transition will hold if Egypt becomes more polarised. Mr Morsi still needs a consensus to govern.

• This article was amended on 27 November 2012. The original said of the arguments used by Morsi's supporters: "None are not without weight."