CAIRO — Mohamed Morsi, the deposed president of Egypt, was sentenced to 20 years in prison by an Egyptian court on Tuesday, in the first verdict handed down in any of the four significant criminal cases brought against him since the military ousted him in 2013.
Mr. Morsi and a dozen other defendants were convicted of inciting violence and directing illegal detentions and torture. The charges stemmed from a night of bloody street fighting between Mr. Morsi’s supporters and opponents outside the presidential palace in December 2012. All of the defendants were members of his administration or Islamists from the Muslim Brotherhood, which supported him.
The ruling illustrated the determination of the government of the current president, Abdel Fattah el-Sisi, to crush the Muslim Brotherhood, the 87-year-old Islamist movement whose candidates received the most votes in presidential and parliamentary elections in 2011 and 2012. The convictions in the case are likely to deepen the alienation of Mr. Morsi’s supporters and make the chances of any reconciliation even more remote.
Prosecutors had also accused Mr. Morsi of premeditated murder and had sought the death penalty, but the court acquitted him of those charges.
Lawyers for Mr. Morsi may appeal, although he has maintained that the new military-led government is illegitimate and that he does not recognize the authority of the courts. Mr. Morsi may also face the death penalty in the other cases against him.
Mr. Morsi has been in detention since July 3, 2013, when the military — led by Mr. Sisi, who was then a general — removed him from the presidency after a year in office.
The street fight at the center of the criminal case was a turning point in the failure of Mr. Morsi’s presidency. Fearing that the courts were about to strike down the constitutional convention his government had organized, just as they had dissolved a previous constitutional committee and Parliament, Mr. Morsi stunned Egypt by decreeing that his own decisions would be immune to judicial oversight until a new charter could be adopted.
His move prompted a huge public reaction, bringing together for the first time his left-leaning and liberal opponents and the old conservative elite that had ruled under his predecessor, Hosni Mubarak. Protesters threatened to storm the palace, and the military and police forces, still dominated by the old guard, refused to protect it. Mr. Morsi’s allies in the Muslim Brotherhood responded by rallying their civilian supporters to protect the palace instead.
The result was a battle of mobs using rocks, sticks, gasoline bombs and at least a few firearms on both sides. At least 10 people were killed; most were supporters of Mr. Morsi, but at least one was an opponent of the Brotherhood, the journalist Al Husseiny Abu Deif.
By the next morning, Mr. Morsi’s civilian supporters had detained and beaten several of their opponents, accused them of various crimes and turned them over to prosecutors, who promptly released them. Mr. Morsi himself appeared to believe that his opponents that night were part of a conspiracy against him.
It was unclear what evidence the court might have found that would tie Mr. Morsi or the other defendants to the actions of their supporters in the streets that night. Most of the trial sessions were closed to the news media, and Judge Ahmed Sabry Youssef, who read the verdict on Tuesday for the three-judge panel that heard the case, did not elaborate.
Mr. Morsi’s supporters said the verdict was itself a crime. “These verdicts are destined to oblivion, in the law and in the Constitution, Mr. Morsi’s son, Osama Mohamed Morsi, 20, said in a telephone interview with the Al Jazeera television network.
“All that is happening now in procedures and verdicts is nothing but one of the ploys that the current regime is using to try to divert the revolutionaries off the path of revolution, the younger Mr. Morsi said. He added that the conviction would be annulled when “the military coup was overthrown, just as politicized convictions handed down under Mr. Mubarak were later set aside.
Amr Darrag, a Brotherhood leader and co-founder of its political arm, said in a statement from Istanbul on Tuesday that the trial was “a travesty of justice, which has been scripted and controlled by the government and entirely unsupported by evidence.
Mr. Darrag urged the United States and Britain to suspend military aid to Egypt, “which is only aiding and abetting Egypt’s descent into brutal autocracy.
Mr. Morsi is the second Egyptian president in three years to be convicted of a major crime. Mr. Mubarak, who was himself ousted by the military after a popular uprising in 2011, was at one point convicted of overseeing the killing of hundreds of protesters by the security forces during his last weeks in power. He was initially sentenced to life in prison, but an appeals court overturned that conviction and ordered a retrial.
Mr. Mubarak, 86, was also convicted of corruption, but he has already served out his jail term in that case. He remains out of sight, presumably in the military hospital where he was held during his detention, but the legal reasons for holding him now are not clear.