: The Jarîmah Qadhaf in Determining the Legal Status of Illegitimate Children. The decision of South Jakarta Religious Court which compared a child born within an unregistered marriage with a child born outside marriage are equal is a real form of rejection of the plaintiff's claim in a lawsuit of the legal status of illegitimate children. From an Islamic criminal law perspective, determining the legal status of illegitimate children contains an element of jarîmah qadhaf or the criminal act of adultery which is prohibited in Q.s. al-Nûr : 4. The legal process in this case still proceeding after the plaintiff expressed an intention to continue to the appeals process at the Jakarta PTA level and if necessary up to the level of the Supreme Court of Cassation. In the process of seeking justice, this will certainly bring benefits to the discourse and dynamics of Islamic family law in the future.