10 human rights defenders from different non-governmental organizations gathered in Istanbul Buyukada for a training workshop and were detained in a police raid on the 5th day of the workshop, on 5 July 2017. On July 17, 2020, they were brought to the prosecutor's office on charges of "committing crime on behalf of the terrorist organization without being a member of the organization" and "membership in an armed terrorist organization". While 8 of 10 defenders were arrested, 2 of them were released on condition of judicial control. The indictment against them was announced about three months later. In the indictment, it was seen that one more rights defender was added among the suspects. The verdict of the case held at the Istanbul 35th High Criminal Court, which led to reactions and campaigns at national and international levels, was held on 3 July 2020. While various prison sentences were given to four defenders, seven defenders were acquitted. 

On 5 July 2017, police raided a workshop on coping with trauma and digital safety, held on Büyükada, an island off the coast of Istanbul. Under the instructions of the Istanbul Islands’ Chief Public Prosecutor’s Office, ten human rights defenders were taken into custody The ‘Istanbul 10’, as they were later called, were all human rights defenders; eight of them were Turkish citizens, one was German and the other was Swedish-Iranian. No one, including their relatives and lawyers were informed about the detention process until thirty hours after it happened. 

The public learned about the detentions only by chance on the evening of 5 July. After twelve days of detention, the workshop participants were interrogated by the prosecutor on 17 July 2017. The prosecutor demanded their arrest on charges of “committing crimes on behalf of the terrorist organisation without being a member” and “being a member of an armed terrorist organisation.” 

The day after the interrogation, the following six were arrested and sent to pre-trial detention: İdil Eser (Director of Amnesty International Turkey), Özlem Dalkıran (Helsinki Citizens Assembly), Günal Kurşun (Human Rights Agenda Association), Veli Acu (Human Rights Agenda Association), Ali Garawi (Swedish human rights trainer) and Peter Steudtner (German human rights trainer). The remaining four were released on probation with an international travel ban: Nalan Erkem (Helsinki Citizens Assembly), Şeyhmus Özbekli (Rights Initiative) İlknur Üstün (Women’s Coalition) and Nejat Taştan (Association for Monitoring Equal Rights). An arrest warrant against four people was issued on 21 July 2017, following the prosecutor’s objection to the initial ruling on their release. Nalan Erkem and İlknur Üstün were taken into custody a second time, from their homes, and later arrested. Nejat Taştan and Şeyhmus Özbekli were released again, with an international travel ban and having to report to the police twice a week during a probation period. 

After three months, on 4 October 2017, an indictment was issued by the Istanbul Chief Public Prosecutor’s Office, charging all the rights defenders with “being a member of an armed terrorist organisation” (Article 314/2 of the Turkish Criminal Code) and “aiding armed terrorist organisations” (Article 220/6 of the Turkish Criminal Code). The Chair of Amnesty International Turkey, Taner Kılıç, had been in pre-trial detention for over a year, charged with “being a member to a terrorist organisation”. Though initially a separate case held before the İzmir 16th Criminal Court, Kılıç, was added as a suspect under the same indictment as the ‘Istanbul 10’. There were several actions from civil society to protest against the detentions. One of them concerned a group of non-profit organisations, who issued a joint press release before the first hearing of the Büyükada case at the Istanbul 35th Criminal Court on 25 October 2017, stating that “The training on coping with trauma and digital security has nothing confidential, has been organised in an open and transparent manner and basically aims to enhance the information and wellbeing of rights defenders. It is about a normal issue, organised everywhere in the world, yet the lawsuit aims to forcibly criminalise the training as well as its participants. “ With the exception of Taner Kılıç, all the rights defenders were released after the first hearing. 

They had been detained for a total of 113 days. At the third hearing, held on 31 January 2018, the court ruled for Taner Kılıç’s release. He was however arrested again on 1 February 2018, following the prosecutor’s objection to the decision. 

At the fourth hearing, held on 21 June 2018, the court ruled for the detention of Kılıç to be continued. After fourteen months of detention, Taner Kılıç was released on 15 August 2018, following an objection to his detention from his lawyer At the 11th hearing on 19 February 2020, the defendants’ arguments on the merits were heard. Prior to the verdict hearing, the UN Special Rapporteur sent a letter to the government of Turkey on June 30, 2020. In the letter; concern was expressed over the trial of 11 rights defenders for terrorism-related crimes. Rapporteur emphasised the negative impact of the case on civil society in Turkey. 

On 3 July 2020, the court sentenced Amnesty International Turkey’s Honorary Chair Taner Kılıç to six years and three months in prison over “terrorist organization membership.” Günal Kuşun, İdil Eser and Özlem Dalkıran were handed one year and 13 months jail terms each over “aiding a terrorist organization.” Nalan Erkem, lknur Üstün, Ali Gharavi, Peter Steudtner, Veli Acu, Nejat Taştan and Şeyhmus Özbekli were acquitted. The rights defenders will appeal the ruling. 

Turkey's government, responded UN special rapporteur on 24 July 2020. In response, it was emphasized that everyone is equal before the law and the courts in Turkey. It was stated that the rights of everybody are guaranteed by the state without discrimination. However, it was stated that this guarantee does not recognize immunity before the law. It was argued that the interpretation of human rights violations made before the convictions go to the high judiciary is premature and biased. The 3rd Criminal Chamber of the Istanbul Regional Court of Justice rejected the appeal of Taner Kılıç, Günal Kurşun, İdil Eser and Özlem Dalkıran on 26 November 2020.  

The 3rd Chamber of the Supreme Court of Appeals overturned the local court's decision on October 17,  2022. According to the decision, Taner Kılıç, Honorary Chair of Amnesty International, was sentenced to prison as a result of incomplete research. Former Amnesty International Turkey director İdil Eser, Human Rights Agenda Association Board member Günal Kurşun and rights defender Özlem Dalkıran had to be acquitted.

The file was sent to the Istanbul 35th High Criminal Court for a retrial.

At the first hearing on March 8, 2023, the court board announced its interim decision after announcing that it complied with the annulment decision. The delegation decided to continue the foreign travel ban on Kılıç and to investigate whether he used ByLock. As soon as the expert report on this issue came, it was decided to send the file to the opinion. The next hearing will be held on June 6, 2023.