Selim Sadak graduated from the Mathematics department of Diyarbakır Eğitim Enstitüsü. Subsequently to his graduation, he worked as a freelancer in Kurdish, English and Arabic.
He is married and has 10 children.
In the 1991 Turkey Parliamentary general election, he joined Leyla Zana, Mahmut Alınak, Hatip Dicle, Orhan Doğan, Ahmet Türk, Sırrı Sakık and Sedat Yurtdaş in the Social Democratic Populist Party and was elected as the member of parliament for Şırnak in the 19th Parliament of Turkey. On 16 June 1994 the Democracy Party was closed down by the Turkish Constitutional Court, and Selim Sadak, along with other members of the party, were put in prison. Based on a decision by the Start Security Court he was sentenced to 15 years in prison in 1995. He was released in 2004 following a European Court of Human Rights decision.
Following his release from prison, him along with Leyla Zana, Hatip Dicle set up the Democratic Society Party, and was elected mayor of Siirt under the Democratic Society Party, receiving 49,43% of the votes in the 2009 local Turkish elections.
In December 2009, however, Turkey banned the DTP due to alleged links with the PKK and Selim Sadak as well as Ahmet Türk, Aysel Tuğluk, Leyla Zana and Nurettin Demirtaş, were banned from politics for 5 years.
In August 2011 he was sentenced in Siirt Criminal Court to five months in prison, a sentence which was later converted to a fine.
On 7 October 2011 he was sentenced in Diyarbakir court to one year and eight months prison for terrorist propaganda in relation to a speech that he made in 2007.
- Selim Sadak kimdir?, Okimdir.com, Erişim Tarihi: 6 December 2008.
- "Siirt Mayor Selim Sadak'a were sentenced to 5 months in prison". Haber Monitor. 2011-08-14. Retrieved 2011-10-14.
- "150 ans de prison pour trois députées kurdes dont Leyla Zana". Le Post. 2011-10-13. Retrieved 2011-10-14.