Among them were seven teenagers aged 15 and 16, who were sentenced to prison terms until they turn 18. The rest most aged 18 to 22 were sentenced to 11 years in prison. Six other Brotherhood members were sentenced to 15 years in prison for inciting the demonstrations.
"We thought they will get a month or something but we were shocked with the 11 years," defense lawyer al-Shimaa Ibrahim Saad said.
The Muslim Brotherhood's political arm, the Freedom and Justice Party, said the sentences are meant to be a "deterrent" for the group's opposition to the military, vowing the verdict "will only increase the determination of the people to get their rights."
Meanwhile, hundreds of secular youth activists protested Wednesday in downtown Cairo against the government's clampdown on dissent. At the center of the crisis is the law issued this week banning any protests or public political gatherings of more than 10 people without a prior police permit, imposing stiff fines and jail terms for violators.
"Those thinking the authoritarian pharaonic style works will find it doesn't anymore," said one protester, Laila Soueif. "There will be a third wave of the revolution much more violent than before. We are witnessing a turning point."
A day earlier, security forces broke up two small activists' protests in Cairo. Security forces beat and dragged women protesters outside parliament.
The images were reminiscent of the days of Mubarak, the autocrat who ruled the country for nearly 30 years and was ousted in a 2011 uprising. Under his rule, police at times focused on humiliating female protesters. Similarly, under the rule of the military that followed his ouster, police broke up an anti-military protest, half-stripping a female protester and stomping on her chest.
After breaking up Tuesday's protest, police detained 14 women, then drove them in a van through the desert where they were dropped off on a remote road in the middle of the night, several of the women said. That too is a tactic used by Mubarak-era police to intimidate protesters.
"They want to terrorize us," said Mona Seif, a prominent activist who was among the 14 women. "I think the interior minister decided to escalate and tell everyone whose family was killed... beaten or anything that I am here, this is how I do business, and if you don't like it, beat your head against the wall."
In the face of the criticism, the Cabinet issued a strongly worded statement saying it is determined to implement the new protest law with "all firmness and force ... so freedom doesn't turn to chaos." It linked it to a "war on terrorism" pointing to the Brotherhood protests and violence by Islamic militants in Sinai.
"There are elements that want to spread domestic chaos in a desperate attempt to hurt the prestige of the state," it said.
The law comes ahead of an election season that will include a referendum on amendments to the Islamist-drafted, Morsi-era constitution. Authorities have shown they are eager to push through the new charter but they could face troubles in the January vote on two fronts.
Secular activists oppose the document because of wider powers it gives the military and the president. The Brotherhood rejects the entire amendment process along with the new government in general and although it has been weakened by a crackdown, it has kept up protests for over 20 weeks and can still mobilize against the document.
On Wednesday, the prosecutor general's office ordered 24 people who were arrested in Tuesday's activist protest to be held for four days for questioning on possible charges of violating the protest law.
In a statement, the prosecutors office accused the protesters of "chanting antagonistic slogans against the state" and refusing to end their rally. It said the demonstration "disturbed traffic and affected citizens' interests," terms mentioned in the protest law as violations justifying police action. It also accused them of attacking a police officer and taking his telephone.
The prosecutor also ordered the arrests of Alaa Abdel-Fattah and Ahmed Maher, two top activists, on suspicion of inciting others to break the protest law, the state news agency MENA said.
In a sign of the Islamists' eagerness to find a common cause with secular activists, the Brotherhood-led coalition supporting Morsi reached out to them Wednesday with a statement denouncing "brutal repression" of the protests the day before, saying the "youth of the revolution stand united."
The spokesman of the Muslim Brotherhood-led coalition, Diaa al-Sawi, said he will contact youth activists to coordinate rallies.
They met a quick rejection, however, from the youth activists, who joined the massive anti-Morsi protests that preceded his ouster.
"A message to the Muslim Brotherhood: we will not put our hands in the hands of those who betrayed and hijacked the revolution," said Hossam Moanis, spokesman of one activist group, the Popular Current.