Ahmed Seif, who is also a lawyer, told AFP he will represent his son and 24 other pro-democracy activists charged with "holding an unauthorised demonstration and aggression against the police."
"The prosecution informed us that he and the 24 others have been referred to the criminal court," Seif said.
No date has yet bet set for the trial but it will be the second of its kind since yesterday when three other prominent secular activists went on trial following a restrictive new law on protests.
These trials by the new military-installed government are seen as a widening of a crackdown on protests which had targeted only Islamists after Morsi's ouster in July.
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Abdel Fattah was arrested on November 28, two days after taking part in a Cairo protest against a provision in the draft constitution that allows military trials of civilians in certain cases.
The other 24 activists were released on bail last week.
Two days before the protest interim president Adly Mansour passed the new law allowing only police-sanctioned demonstration, a move that triggered an international outcry.
Abdel Fattah was previously jailed under Mubarak, the military junta that immediately ruled Egypt after his overthrow, and also under Morsi.
The trial that opened yesterday of Ahmed Maher, Ahmed Douma and Mohamed Adel is the first of secular activists since Morsi was overthrown. A verdict in their case is expected on December 22.
The three activists are accused of several charges including assaulting police officers and joining a protest without seeking a police permit as required by the new law that was introduced after Egypt lifted a three-month state of emergency.