- Government: Law is necessary at a time of frequent attacks
- Rigts groups: The measures will be counterproductive
The law gives Egyptian authorities powers usually reserved for states of emergencies, Amnesty International said.
It "effectively bans the rights to freedom of expression, peaceful assembly and association," the group said.
The law imposes hefty fines for journalists if their accounts of terrorism-related cases contradict the official version.
The government insists the law is necessary at a time when militants are increasingly launching brazen and deadly attacks. The frequency of the attacks picked up after Egypt's army overthrew President Mohamed Morsy -- a former Muslim Brotherhood leader -- following a popular uprising in July 2013.
Hundreds of Egyptian troops have since been slaughtered.
'Decrees that aim to stifle dissent'
For rights groups, the measures would be counterproductive.
"More attacks on civil and political rights and freedoms by security institutions won't be a successful solution in the face of all these [terrorist] threats," 14 Egyptian rights groups said in a joint statement in July when the legislation was drafted by the Cabinet.
The law gives officials broad immunity from prosecution if they use lethal force, even when it's not to protect lives, said the Geneva-based United Nations' International Commission of Jurists. In addition, it grants prosecutors sweeping surveillance and detention powers, the group said.
"The promulgation of the Counter-Terrorism Law by President el-Sisi expands the list of repressive laws and decrees that aim to stifle dissent and the exercise of fundamental freedoms," said Said Benarbia
, director of the ICJ's Middle East and North Africa Program.