Egypt's Court of Cassation overturned a life sentence against deposed President Mohamed Morsi of the Muslim Brotherhood and ordered a retrial in the case that revolves around the accusations of espionage with Palestinian group Hamas.
The court overturned a death sentence against Morsi in a separate case, meaning he no longer faces execution.
Democratically elected after the 2011 uprising, Morsi was overthrown in mid-2013 by Abdel Fattah al-Sisi following mass protests against his rule and was immediately arrested. He remains in jail on separate convictions.
Morsi was one of 22 high-ranking Muslim Brotherhood officials and supporters convicted last year of spying for fellow-Islamist group Hamas.
The Court of Cassation's ruling overturns all convictions in the case including life sentences against Mohamed Badie, the General Guide of the Muslim Brotherhood, and 15 others. Senior Brotherhood officials Kheirat al-Shater and Mohamed al-Beltagi as well as Morsi aide Ahmed Abdelatti had originally been sentenced to death in the case and also saw their convictions dropped on Tuesday.
Since toppling Morsi and winning a presidential election the following year, Sisi, a former general, has crushed dissent.
Security forces killed hundreds of Morsi supporters in a single day in 2013, in one of the bloodiest incidents in the country's modern history.
Thousands of Muslim Brotherhood supporters have since been detained and hundreds have received death sentences or lengthy prison terms in mass trials condemned by human rights groups as legally flawed and politically motivated.
The Egyptian government says that it does not interfere in the work of the judiciary. Egypt's judiciary says it is independent.
The government deems the Brotherhood, Egypt's oldest Islamist movement, a terrorist group. The Brotherhood says that it is committed to peaceful activism.