The trial of 11 human rights activists accused of terrorism kicked off in the Turkish city of Istanbul on October 25, with the defendants facing up to 15 years in jail.
The activists -- who include the two top figures with Amnesty International in Turkey as well as a German citizen and a Swedish national -- face charges that include seeking to create "chaos in society" and membership in and aid to an "armed terrorist organization."
Berlin has described the case as "completely incomprehensible" and "absurd."
London-based Amnesty International said the activists were detained "for no reason except for their belief in human rights" and mobilized celebrities calling for their release.
The activists include Amnesty Turkey Director Idil Eser and its chair, Taner Kilic. Ten of them have been behind bars since a police raid in July on a workshop run by Amnesty.
The case emerged amid concerns that Turkey is sliding toward authoritarianism under President Recep Tayyip Erdogan.
A state of emergency was imposed after a failed coup in July 2016 blamed by Turkish authorities on U.S.-based cleric Fethullah Gulen, who denies involvement.
Based on reporting by Reuters and dpa