The Constitutional Court’s Decision No. 46/PUU/XIV/2016 which rejected the petition of petitioners to broaden the meaning of zina (fornication) in the Criminal Code of Indonesia has been becoming an interesting issue to be discussed. Some researchers have argued that the Constitutional Court must use its authority to conduct a break-through in responding the crucial legal issue. On the other hand, the Court asserted that widening the meaning of zina in the Criminal Code of Indonesia is not its authority. The current paper aims at discusing further the ratio decidendi of the Decision of the Constitutional Court which contains the element of open legal policy and its implication to national legislation system. The research is a normative legal research which uses statute approach and case law approach. The result of research shows that firstly, the concept of open legal policy in the Constitutional Court’s decisions does not have a clear limitation which implies uncertainty of its implementation in the Court’s decisions and the national legislation system. Secondly, the Decision of the Constitutional Court with open legal policy also shows that on one hand, there is a trend of using judicial activism among the constitutional judges and on the other hand, some constitutional judges also use judicial restraint approach as their reasons which results uncertainty of law in Court’s decision. This paper recommends that there should be a furthert study on design model of open legal policy in the Constitutional Court decisions and its implication to national legislation system.