An Alexandria court rejected on Sunday a second legal challenge presented by activist Mahinour El-Masry and two other defendants against their 15-month prison sentences.
In May 2015, an Alexandria court convicted El-Masry, along with journalist Youssef Shaaban and poet Loay El-Ahwagy, of storming a police station in 2013 during the tenure of ousted Islamist president Mohamed Morsi.
A previous challenge to the ruling was turned down on 20 September.
Defendants can still lodge other appeals against the verdict.
This is not the first time that El-Masry has received a prison sentence.
The human rights lawyer and revolutionary socialist activist was released from jail in September 2014 after serving four months as part of a six-month sentence on charges of illegally protesting during the Khaled Said murder retrial in December 2013.
Khaled Said was beaten to death by police officers in Alexandria in 2010. Pictures of his brutalised face, that were widely shared on social media, played a role in sparking the 2011 uprising that toppled long time autocrat Hosni Mubarak.
While in jail, El-Masry was awarded the 2014 Ludovic Trarieux Award for her contributions to the defence of human rights.