The implementation of Constitutional Court Decisions often creates polemics in the Indonesian Constitutional System, especially those relating to the Implementation of Constitutional Court Decisions related to Ministries / Institutions where in implementing Constitutional Court Decisions can only be done through legal products issued internally by ministries / institutions related and often overlaps with legislation that has not been amended. This is caused by the relevant Ministries / Institutions not having the authority to make changes to the Law in which the authority is owned by the President as the executive and the House of Representatives as the legislative. While the Court's Decision The constitution often has a direct impact and can bring great changes to the people in obtaining justice. This type of research is used Normative Juridical Research Method, namely by examining library materials. This study uses a philosophical approach because the object of the study examines the principle of legal certainty in the implementation of the Constitutional Court's decision through the regulation of state institutions and Perppu. In addition, the legislative approach is also used to find out the reasons for the Constitutional Court's decisions that often overlap in implementation.Implementasi Putusan Mahkamah Konstitusi seringkali menimbulkan polemik dalam Sistem Ketatanegaraan Indonesia,terutama yang berkaitan dengan Pelaksanaan Putusan Mahkamah Konstitusi yang terkait dengan Kementerian/Lembaga yang di mana dalam melaksanakan Putusan Mahkamah Konstitusi hanya dapat dilakukan melalui produk-produk hukum yang dikeluarkan secara internal oleh kementerian/lembaga terkait dan seringkali mengalami tumpang tindih dengan  Peraturan Perundang-undangan yang belum mengalami perubahan.Hal ini disebakan Kementerian/Lembaga terkait tidak mempunyai kewenangan dalam melakukan perubahan  Undang-undang yang di mana kewenangan tersebut dimiliki oleh Presiden sebagai eksekutif  dan  DPR selaku legislatif.Sedangkan Putusan Mahkamah Konstitusi seringkali berdampak langsung dan dapat membawa perubahan besar bagi rakyat dalam memperoleh keadilan. Jenis Penelitian yang digunakan Metode Penelitian Yuridis Normatif,  yaitu dengan meneliti  bahan  kepustakaan.  Penelitian  ini  menggunakan  pendekatan  filosofis karena  objek  penelitian  mengkaji  asas kepastian hukum dalam implementasi putusan MK melalui peraturan lembaga negara dan perppu.  Di  samping  itu,  juga  digunakan pendekatan perundang-undangan untuk mengetahui alasan putusan MK seringkali mengalami tumpang tindih dalam implementasi.