CAIRO (AP) — An Egyptian court on Wednesday convicted a prominent activist from the 2011 uprising of organizing an unauthorized protest and assaulting a policeman, sentencing him to 15 years in prison, in the latest blow to liberal activists at a time of rapidly eroding freedoms.

The sentence against Alaa Abdel-Fattah is the toughest against any of the secular activists behind the 18-day uprising that ended Hosni Mubarak’s 29-year reign. It is also the first conviction of a prominent activist since former army chief Abdel-Fattah el-Sissi took office as president on Sunday.