A criminal record certificate (commonly known as a police record) is asked for in job applications, tenders, licenses and many other official procedures. There's no need to go to the courthouse: the Ministry of Justice issues this document through e-Devlet, and the document is free.
The document carries a barcode number. The institution you give it to can use your Turkish ID number and this barcode to view the original document in the system and verify it — so printing it out and handing it over is enough, and no wet signature is required.