At the founding of the Republic, the Turkish legal system was primarily based on the legal system of Continental Europe. Over time, it developed into a unique system using the written multi-layered legislative framework of the Turkish Constitution, statutory codes, and secondary legislation as the primary sources of law. The interpretation of these primary sources of law by the courts depends heavily on both expert academic interpretation in theory and court precedents in practice as persuasive authorities. Certain controlling high court decisions also carry the force of law.