In recent decades, the growing number of Muslim immigrants in Western countries has led to the invocation of certain rules derived from Islamic jurisprudence within new legal frameworks and before the courts of non-Muslim states. One of the most significant manifestations of this development is the filing of mahr claims by Muslim women before foreign courts- a phenomenon that has compelled courts of the forum to examine the legal nature of mahr and to reconcile it with corresponding institutions of domestic law. The aim of this article is to address the crucial role of functional characterization in private international law, with a focus on examining the case law of German courts in determining the legal status of mahr in cases involving a foreign element. Over the past half-century, in response to claims for the paymentof mahr, German courts have sought -by adopting a functional characterization approach- to examine the functions of mahr and to compare it with corresponding institutions of domestic law. Through this process, they have aimed to identify the legal nature of mahr and to determine the law applicable to it under rules of conflict of laws. A pivotal moment in this effort was the 2009 decision of the German Federal Supreme Court (Bundesgerichtshof), which characterized mahr as a ‘marriage effect’ under Article 14 of the Introductory Act to the Civil Code (EGBGB). Nevertheless, even after this decision, the German legal system’s approach to the subject continues to evolve. This study, drawing on developments in German law regarding the mahr, emphasizes the importance of the characterization process and its decisive role in private international law, reflecting the nuances of this stage, particularly in cases where multiple connecting factors from diverse cultural contexts are involved and the subject of characterization lacks a direct counterpart or equivalent in the law of the forum.