The law came amid a widening legal and security crackdown on supporters of Morsi that has left hundreds dead and thousands arrested on various charges, including inciting violence.
New-York based Human Rights Watch said the new law empowers the security agencies to crush the right of Egyptians to protest against their government.
They say authorities are now also targeting secular activists who have continued to be critical of successive leadership since Hosni Mubarak's 2011 ouster—like the three activists sentenced Sunday.
Heba Morayef, Egypt Director for Human Rights Watch, said the case against the three, a similar referral of 24 other protesters and a leading blogger in Cairo to trial and others in the country's second city Alexandria, appears to be the beginning of a new trend of targeting high profile activists who were behind the Jan. 25, 2011, protests.
The protesters had used rampant police abuse as a rallying cry against Mubarak and his nearly 30 years in power.
