The protests were held in defiance of - and in protest against - a new law requiring police approval for protests. The organisers had not sought prior permission. A number of prominent activists – including lawyer Zyad El-Elaimy – turned themselves in to police shortly after the demonstration, in solidarity with the protest organisers. El-Elaimy said they were questioned by prosecutors late on Tuesday. Among those arrested were Mona Seif, founder of a campaign against military trials of civilians, and Ahmad Harara, an activist who lost his eyes to birdshot during protests against former president Hosni Mubarak in 2011 and the military junta that took power after Mubarak's fall. A number of groups have said they will hold further demonstrations on Wednesday against the protest law and police abuses.
The police measures sparked condemnation from many observers. Thirteen members of the panel drafting Egypt's new constitution have suspended their work in protest at the detentions, state news agency MENA reported. Dozens of lawyers have begun an open-ended strike at the lawyers' syndicate in protest at the arrests, Al-Ahram Arabic news website reported.