Problems arise regarding the struggle for inheritance, particularly when an heir feels that s/he has received the inheritance fairly, or there is disagreement between heirs on the inheritance law. Often grandchildren feel that their rights as substitute heirs have not been fulfilled, and they approach local Religious Court to claim their inheritance rights. The current study discusses a case of substitute inheritance where grandchildren attempt to obtain substitute inheritance for a property. The focus of the study was the Supreme Court's decision Number 185 K/AG/2009. A normative juridical approach method was used and analytical and descriptive techniques were adopted to examine the facts of this qualitative study. Secondary data sources were used to collect data from legal archives, libraries and data bases. Primary data was also collected through informal discussion with the Law officials. The study highlights how a religions court recognized grandchildren as legal heirs (substitute heirs) and permitted them to replace the previous heirs, who were their parents. The study describes how the substitute heirs made efforts to conduct initial consultations or mediation with the parties. When they did not succeed, they filed a lawsuit in the Religious Court, in accordance with Law Number 3 of 2006 and the Judge's consideration at the Supreme Court level in deciding the case Number 185/K/Ag/2009. The case was also filed with reference to Article 185 of the Compilation of Islamic Law which stated that a child can replace the position of his parents who died first as a substitute heir provided that the portion received did not exceed the share of the heirs equal to the heirs being replaced. The verdict was not accepted by the Defendants and a cassation was filed in the supreme court. This study will prove to be a good reference study and would serve as a precedence in similar cases.