This study aims to analyze the implementation of Progressive Legal Theory (PLT) indicators on the Constitutional Court judges’ decision in Indonesia in decision No.30-74/PUU- XII/2014 concerning restrictions on marriageable age and reconstruction of PLT in the study of the operational legal system in Indonesia. This study is empirical with primary data in the form of free-guided interviews and secondary data by analyzing judges’ decisions in content analysis. The results of this study showed that eight judges had implemented indicators of PLT, namely indicator 3, 5, 8, and 10. While indicators 1, 2, 4, 6, and 7 had not been implemented. One judge had a dissenting opinion with the reasons: The decision has progressivism values; The Court’s decision implements ‘the law as a tool of social engineering’; and the different regulations regarding the marriage age limit extend legal uncertainty. The implementation of PLT indicators on judges who had dissenting opinions in their entirety matched the PLT indicators. The findings showed that decision No. 30- 74/PUU-XII/2014 had not fully used ten indicators of PLT. The reconstruction of the Progressive Legal Theory in the study of the operation of the legal system in Indonesia was formulated with 3 main indicators namely living law, legal system, and legal harmonization.