Ruslan Mesutov, Ruslan Nagayev, Eldar Kantemirov and Lenur Khalilov will remain in custody until November 5.
The lawyers and the defendants themselves consider this step illegal.
The open court session took place in Simferopol, as the "court" continued to look into the case of five men charged with membership in Hizb ut-Tahrir, the Islamist organization that is banned in Russia.
Ukraine repeatedly responded to the searches and detentions in the annexed Crimea; Ukrainian law enforcers opened criminal cases over these facts, and the Ukrainian Foreign Ministry officially protested against the searches and arrests of Crimean Tatars there, urging the international community to increase the sanctions' pressure on Russia.
Hizb ut-Tahrir, meaning "Party of Liberation," is an international Islamist movement seeking to unite Muslims under one Islamic caliphate. Founded in 1953, it considers itself a non-violent political party. The movement states that its goal is to peacefully convert Muslim nations to Islamist political systems. Hizb ut-Tahrir praises the concept of jihad but insists that it does not use material power as a weapon. The group publicly disavows efforts to achieve its goals of a caliphate through violent means.