On the surface, the latest rock-throwing incident in Cairo that injured over 100 is explained by the court ruling that acquitted former officials charged with killing protesters in the uprising that ousted Hosni Mubarak last year. But even before the ruling, things were simmering. President Mohamed Morsi's boast earlier in the week that he had carried out much of what he had promised for his first 100 days angered many Egyptians who had high expectations. They point to congested traffic, fuel shortages, garbage on the streets, shaky security, a faltering economy, and incessant strikes and sit-ins by Egyptians of all walks of life, mostly for higher wages, as examples of Morsi's failure to deliver. Then there is the constitution which must be agreed upon before a new parliament can be elected and which is being drafted by mostly Islamists accused of trying to impose their dominance and to Islamize the state. Many secular-minded Egyptians and minority Christians also worry that Morsi and his Islamist supporters will seek to impose religious restrictions on society. These factors combined to instigate the first street violence since Morsi took office in June. The final straw was this week's acquittal of 24 of Mubarak's old guard for involvement in the Battle of the Camel in February last year which killed 11 people. Many blamed the general prosecutor, perceived as a Mubarak loyalist, for not securing convictions. What followed was pure farce: To appease the public, the president tried to move prosecutor-general Abdel Maguid Mahmoud out and make him ambassador to the Vatican, because Egyptian law prevents Mahmoud from being dismissed. Mahmoud denounced the move and decided to stay put. Removing Mahmoud, who was appointed by Mubarak, has been a longstanding popular demand since last year's uprising, and it has become increasingly pressing with every acquittal granted to Mubarak-regime figures held for killing unarmed protesters. However, according to the Egyptian legal system, the president does not have the power to dismiss the prosecutor general from office but the latter has the right to ask to be relieved of his duties. Morsi can send him somewhere else, but only if there is agreement. Morsi's decision is similar to his move early in his presidency to restore the Islamist-dominated parliament despite a decree by the Supreme Constitutional Court which dissolved it over election law violations. He could not bring it to session. Morsi must by now know the limits of his powers - what he can do and what he cannot. If his authority was properly defined, he would not now be in the embarrassing situation of firing an official who defiantly stays on, and can do so legally. Changing the prosecutor involves an independent judicial move. The president cannot interfere in the judiciary system every time he or the general populace or both disagree with a court ruling. That would be total chaos. The president should not intrude in the affairs of the courts, or else the government will not be much different from the kind of system the revolution threw out. Meanwhile, the clash comes as criticism against Morsi has been growing since he was inaugurated. He must address the reasons for the violence, but he must do so carefully and with discretion.