Every year in early March, the Islamist group Hizb ut-Tahrir's branch in Turkey holds an international conference to commemorate the Ottoman caliphate, which was abolished in 1924.

This year’s conference, set for March 5 in Istanbul, was to be titled “Why Does the World Need the Caliphate?” Mahmut Kar, media bureau chief of Hizb ut-Tahrir Turkey, had applied for permission from local authorities to hold the conference under the standard procedure. Yet on March 1, news broke that Kar and one of his colleagues, Osman Yildiz, were taken into custody.

“After the announcement for the conference was made, extremely secular Kemalist media outlets started spreading news against the event and pressuring the government," Kurtulus Sevinc, a member of Hizb ut-Tahrir’s media bureau, told Al-Monitor. "Authorities soon informed us that our conference was banned. Kar was invited to the police headquarters to receive this official decision, yet, to all of our surprise, on the orders of a prosecutor, Kar and Yildiz were detained on March 1.”

On March 6, 300 Hizb ut-Tahrir supporters, including Kar's family members, stood in quiet protest in front of the police headquarters in Istanbul demanding the release of Kar and Yildiz, saying that if the men remained in custody, the police could detain the supporters as well. To everyone’s surprise, police did take all the protesters, including women and young children, into custody. The next day, the women and children were released, and later, all but three of the 300 male supporters were let go. Now, a total of five members are in custody. Sevinc said Yildiz was allowed to meet with his wife briefly and told her they feared they would be held in custody for another 15 days.