Abstract: "Marriage Isbat" is the determination of a marriage. The essence of the marriage certificate is the determination that a marriage has occurred and not the legalization of a marriage. The meaning of ratification and determination have different legal consequences. Interpreting Marriage Isbat by stipulation shows that the process of itsbat nikah is solely carried out for an administrative function. The theory of the rule of law and the theory of justice are the basis for analysis of the application of law as a legal construction in considering cases of consanguinity marriages, so a wise and appropriate juridical analysis and application of law is needed.