4.  The applicants were born in 1967, 1965 and 1972 respectively and at the time of lodging their applications they were serving their prison sentences in the Muş E-type prison. 5.  On 6 and 7 March 2006 each applicant sent a letter to the Ministry of Justice, referring to the imprisoned leader of the PKK, Abdullah Öcalan, by using the honorific “sayın”, meaning esteemed. 6.  Pursuant to the Regulations on the administration of penitentiary institutions and the execution of sentences, the applicants were found guilty of breaching prison order by the Erzurum H- type Prison Disciplinary Board (referred hereafter as “the Board”). 7.  On 5 April 2006 the applicants were each sentenced to 12 days’ solitary confinement on the orders of the Board, on account of the statements in the above mentioned letters. 8.  On 17 April 2006 the Erzurum Enforcement Judge rejected the applicants’ objections. 9.  On 30 June 2006 the Erzurum Assize Court upheld the judgment of 17 April 2006. 10.  Furthermore, on 4 July 2005 a disciplinary sanction was imposed on the first applicant, as he avoided visits and telephone calls to protest against the detention conditions of Öcalan. He was accordingly banned from receiving visitors for 2 months. On 21 October 2005 and 14 November 2005, respectively, the Erzurum Enforcement Court and the Erzurum Assize Court rejected the first applicant’s appeal requests.