KONSTITUSIONALITAS PENGUJIAN UNDANG-UNDANG HASIL RATIFIKASI PERJANJIAN INTERNASIONAL OLEH MAHKAMAH KONSTITUSI PERSPEKTIF SIYASAH QADHA’IYYAHNIM.: 20103070096Muhammad Fadhil Irvansyah Antero PersadaauthorThe authority of the Constitutional Court (MK) to review laws ratifying international treaties, along with the implications of this authority for the protection of citizens constitutional rights and the supremacy of the constitution, remains a subject of ongoing debate within Indonesian constitutional law. This debate arises from the position of ratification laws at the intersection of national and international law, particularly regarding the possibility of reviewing them against the 1945 Constitution of the Republic of Indonesia. This study examines the constitutional perspective on the Constitutional Court's review of laws ratifying international treaties and analyses the implications of such reviews from the perspective of siyasah qadha’iyyah (Islamic judicial policy). This study employs a normative-juridical approach, utilising a literature review method that examines relevant legislation, legal doctrines, and Constitutional Court rulings. A systematic analysis is conducted to understand the basis of the Court's authority and its impact on the relationship between national ,international law and fiqh siyasah. The result of this research indicate that the Constitutional Court possesses the constitutional authority to review ratification laws because, once ratified, international treaties become part of the national legal system in the form of statutes that must comply with the constitution. Such review serves as a crucial mechanism for ensuring the conformity of legal norms with the 1945 Constitution while simultaneously protecting citizens' constitutional rights. However, the invalidation of a ratification law by the Court applies only within the domestic legal sphere and does not automatically terminate Indonesia's obligations under the international treaty in question. The Court's authority to review ratification laws embodies the principle of constitutionalism, which establishes the constitution as the supreme law of the state. From the perspective of siyasah qadha’iyyah, this role reflects the function of the judiciary in safeguarding the constitution, protecting citizens' rights, and upholding the principles of the rule of law.342 Hukum Tata Negara2026-08-19UIN SUNAN KALIJAGA YOGYAKARTA;FAKULTAS SYARI’AH DAN HUKUMThesis