The marriage of underage girls is among the most challenging contemporary jurisprudential-legal issues, standing in conflict with the principle of justice and human dignity. This research, employing a descriptive-analytical method, aims to conduct a jurisprudential-legal analysis of this phenomenon in light of the principle of justice. Findings indicate that although traditional foundations permit the marriage of minors with the consent of a compulsory guardian, the principle of justice, as the axis of legislation and a meta-jurisprudential rule, enables a re-examination of these rulings. On one hand, the confirmatory nature of marriage and the centrality of 'ma'ruf' (what is commonly recognized as good) in Sharia necessitate 'rational maturity,' which is not achieved in children. On the other hand, in the present era, the marriage of underage girls, due to its numerous social, psychological, and physical detriments, the violation and deprivation of children's rights, its conflict with family stability, and existing legislative gaps and contradictions, constitutes a clear example of oppression and injustice, contradicting principles such as 'la darar' (no harm) and 'la haraj' (no excessive hardship).

By elucidating the position of the principle of justice as an 'implicit qualifier' (mukhassis libbi) in limiting the evidence for guardianship, the present study proposes novel solutions. These include redefining the criterion for childhood by focusing on 'rational-psychological maturity' instead of a fixed age, legal reforms, establishing specialized committees in family courts, recognizing an 'absolute right to annul' the marriage after reaching puberty, and declaring the 'absolute impermissibility' of any form of sexual utilization of a child. The conclusion is that, with the change in the subject and the instances of justice and injustice, the ruling on child marriage requires fundamental revision. Achieving justice necessitates an interaction between jurisprudence and the findings of human sciences, along with the enactment of protective laws.