The transformation of Islamic family law in national legislation represents a form of constitutional ijtihad. Ijtihad refers to the exertion of utmost effort to produce legal rulings based on conclusions drawn from the Qur'an and Sunnah. This endeavor accommodates the values of Sharia while ensuring inclusive access to justice, protection for vulnerable groups, and the strengthening of legal institutions. Countries with Muslim-majority populations, such as Indonesia and Egypt, have demonstrated that constitutional ijtihad can serve as a means of harmonizing religious norms with international legal standards, in line with the mandates of SDG 16. In practice, the implementation of constitutional ijtihad in Islamic family law also faces several challenges, including cultural resistance, limited institutional capacity, and tensions between religious authorities and the state. Nevertheless, ijtihad remains valid even in the presence of differing ijtihad opinions [17] .

Law functions as a means of social control, social engineering, and social welfare. It is expected to serve as an "agent of change" or alat at-taghyir-a tool of transformation, a determinant, a shaper, and a pioneer in guiding social interactions and behavior. This ideal role of law can be realized when it first assumes its position as a means of social engineering and social control. Before a law can be applied within a region or country, it must first be formalized as positive law in the sense of legis, legality, and qanuniyah. In Islamic legal terminology (fiqh), this process is referred to as taqnin [18] . Some scholars of fiqh define taqnin as the authoritative codification of a set of laws by the governing authority, which possesses binding power to regulate life, relationships, and conduct among people in society [19] .

One manifestation of legal formalization is found in the context of Islamic Family Law. To date, many Muslim-majority countries have codified Islamic family law into national legislation governing matters related to the family life of Muslims. However, this development remains controversial, often reflecting tensions between classical Sharia values and the demands of modernity [20] .

The History and Main Characteristics of Islamic Family Law in Indonesia

Indonesia has a unique history in the development of Islamic family law. As the country with the largest Muslim population in the world, Indonesia integrates Islamic law into its national legal system through various legislative regulations. The transformation of Islamic family law in Indonesia can be divided into several phases: the colonial period, the post-independence period, and the reform era. Each phase reflects a different adaptation to societal needs and political developments [21] .

Islamic family law formalized in the Compilation of Islamic Law (KHI), which was enacted through Presidential Instruction No. 1 of 1991, represents a significant milestone in the transformation of Islamic family law in Indonesia. The KHI covers three main areas: marriage, inheritance, and endowments (waqf) [22] .

Methodology of KHI Compilation

The Compilation of Islamic Law (KHI) was developed through a comprehensive methodology that integrates classical fiqh sources, fatwas issued by Indonesian scholars, and existing decisions of religious courts [23] .

References to Various Fiqh Schools

The KHI draws upon a range of fiqh texts, primarily from the dominant Shafi'i school, but also includes references from the Hanafi, Maliki, Hanbali, Zahirī, and other schools. The aim is to build consensus and minimize inter-school differences within the Indonesian context [24] .

Pluralistic Character of KHI

The KHI reflects the pluralistic nature of Indonesian society by accommodating various madhhab opinions and local Islamic legal traditions [25] . Not a Final Product, but Open to Refinement. As a result of collective ijtihad, the KHI is not a final or closed product; it remains open to revision and improvement in response to changing times and contexts [26] .

The History and Main Characteristics of Islamic Family Law in Egypt

The history of family law reform in Egypt began with the enactment of Law No. 25 of 1920, which regulated alimony and divorce, followed by Law No. 25 of 1929, which expanded women's rights to initiate divorce. These codifications marked a shift from the traditional fiqh-based legal system to a more structured state legal framework. The reforms were influenced by legal modernization efforts in Turkey and the need to adapt Islamic law to changing social realities [27] .

Contemporary transformation has continued, especially after the 2011 revolution. The new 2014 Constitution affirms the principle of gender equality, and courts have increasingly applied the principle of "the best interests of the child" in custody cases. However, resistance from conservative groups and ongoing tensions between state law and religious norms persist. Overall, the transformation of family law in Egypt reflects a complex effort to balance Islamic tradition with the demands of modernity. Although significant progress has been made in terms of women's rights and legal structures, the reform process continues to face various social and political challenges. Further studies are needed to understand the long-term impact of these reforms on Egyptian society. The family law system in Egypt is governed by the Qanun al-Ahwal al-Shakhsiyyah (Personal Status Law) [28] .

Islamic Family Law in Egypt has several key characteristics:

a. Islamic Family Law in Egypt has several key characteristics: a. Sources of Law. Egypt adopts the Hanafi school as its official madhhab; however, in practice, it also incorporates opinions from other schools of thought (talfiq) when deemed necessary for public interest (maslahah).

b. Minimum Age of Marriage. Egypt sets a relatively high minimum age for marriage compared to classical fiqh interpretations: 18 years for males and 16 years for females.

c. Marriage Registration. Marriage registration is legally required, and unregistered marriages are not recognized as legally valid within the Egyptian judicial system.

d. Women's Rights. Family law reforms in Egypt place special emphasis on enhancing women's rights within marriage, including the right to stipulate specific conditions in the marriage contract [29] .

Transformation of Islamic Family Law in Legislation Toward Achieving SDG 16: Comparative Study of Indonesia and Egypt

The transformation of Islamic family law in the contemporary era shows an interesting dynamic between the preservation of classical sharia values and adaptation to the demands of modernization. Indonesia and Egypt, as two Muslim countries with strong traditions of Islamic jurisprudence, have undergone a significant process of transformation. Here are five main aspects of this transformation to provide a comprehensive picture of the development of contemporary Islamic family law.

Age Limit for Marriage

Indonesia experienced a fundamental transformation with the enactment of Law No. [16] of 2019, which changed the minimum age for marriage from 16 years to 19 years for women, equalizing it with men. This change is a response to the high rate of child marriage and aims to protect children's rights and improve the quality of future generations. The Supreme Court, through SEMA No. 1 of 2020, also tightened the criteria for marriage dispensation, requiring more comprehensive consideration of physical, psychological, and economic readiness. This transformation reflects Indonesia's commitment to integrating child protection with Islamic values that emphasize welfare [30] .

Egypt maintains an age limit of 18 years of marriage for men and women as set up in Law No. 143 of 1994. However, there is intensive discussion among Al-Azhar scholars about the possibility of reviewing this regulation to accommodate contemporary social realities. The fundamental difference lies in the implementation approach. Egypt places more emphasis on strengthening administrative mechanisms and socialization, while Indonesia takes more progressive legislative steps

In the context of constitutional ijtihad, Egypt and Indonesia demonstrate significant dynamics in responding to the issue of the legal minimum age of marriage as part of efforts to achieve Sustainable Development Goal (SDG) 16, particularly in terms of justice and legal protection for children. In Indonesia, the amendment of the legal minimum age of marriage for women from 16 to 19 years through the revision of the Marriage Law No. 1 of 1974 to Law No. 16 of 2019 reflects the state's commitment to curbing child marriage practices and strengthening legal protection. Meanwhile, Egypt, through the Child Protection Law No. 126 of 2008, sets the minimum age for marriage at 18 years, although in practice, legal and cultural loopholes still allow for underage marriages to occur. This comparison shows that although both countries have established progressive legal frameworks, the effectiveness of implementation and law enforcement remains the key to ensuring that the transformation of Islamic family law truly supports the realization of just, inclusive, and responsive institutions as targeted in SDG 16 [31] .

Marriage Registration

Marriage registration in Indonesia has undergone significant modernization through the SIMKAH (Marriage Management Information System) program launched in 2019. This digital system integrates marriage registration with population administration and provides real-time access to the public. Minister of Religious Affairs Regulation No. 20 of 2019 concerning Marriage Registration also strengthens the legal aspects of registration with stricter administrative sanctions for violations¹¹. This transformation reflects Indonesia's efforts to realize an orderly administration that is in line with the principle of maslahah in Islam [32] .

Egypt has long made it mandatory to record marriage through Law No. 1 of 2000. The latest transformation includes the digitization of the registration system and integration with the national population database. The uniqueness of the Egyptian system lies in the active involvement of Al-Azhar in the process of verifying and validating marriages, ensuring compliance with Sharia provisions. This is different from Indonesia, which relies more on the role of the KUA and administrative supervision of the Ministry of Religious Affairs.

Marriage registration ensures justice, legal certainty, and the establishment of inclusive institutions. This is closely aligned with efforts to achieve Sustainable Development Goal (SDG) 16. In Egypt, the obligation to register marriages is regulated by Law No. 1/2000 on Litigation Procedures in Personal Status Matters, which emphasizes the importance of an official marriage certificate as valid legal evidence to protect the rights of women and children. Meanwhile, in Indonesia, the obligation to register marriages is stipulated in Article 2(2) of the Marriage Law No. 1 of 1974, reinforced through digital innovations such as SIMKAH (Marriage Management Information System) to enhance accountability and public accessibility. Both countries demonstrate that marriage registration is not merely an administrative requirement but a vital instrument to ensure legal protection and support the goals of SDG 16, namely the creation of a peaceful and just society [33] .

Polygamy Regulations

Indonesia maintains relatively strict regulation of polygamy through Law No. 1 of 1974 and the Compilation of Islamic Law. The latest transformation includes strengthening the polygamy permit procedure through Minister of Religious Affairs Regulation No. 19 of 2018, which tightens the requirements and application procedures [34] .

Religious courts are given broader authority in assessing the appropriateness of polygamy, including economic aspects, justice, and the consent of the first wife. This approach reflects a progressive interpretation of the verses on polygamy that emphasize the principle of justice.

Egypt has undergone a more conservative transformation in regulating polygamy. Law No. 25 of 2019 strengthened the first wife's right to know and give consent to her husband's polygamous plans. A mandatory notification system was introduced, whereby a husband must officially notify his first wife before remarrying. While not prohibiting polygamy, this regulation provides better psychological and legal protection for women.

In Egypt, the restriction of polygamy is emphasized through the requirement to notify the first wife and the involvement of the court if the wife objects, as stipulated in Law No. 100/1985. This law upholds the wife's right to file for divorce if she does not consent to the practice of polygamy. In Indonesia, Law No. 1 of 1974 (Articles 4-9) and the Compilation of Islamic Law impose stricter regulations on polygamy by requiring valid reasons, financial capability, and the wife's consent, all of which must be assessed and approved by a religious court. Both legal systems demonstrate that the restriction of polygamy is not only intended to uphold the principle of maslahah (public interest) in Islamic law but also to protect the rights of women and children and to ensure substantive justice, in line with the goals of SDG 16 to strengthen fair and non-discriminatory legal systems [36] .

Restrictions on Divorce by Husband

Indonesia developed a divorce restriction mechanism through mandatory mediation based on PERMA No. 1 of 2016. This transformation aims to reduce the divorce rate and strengthen the family institution. The Religious Court also developed jurisprudence that emphasized peace efforts and protection of the wife's rights in the divorce process. The concept of "responsible divorce" became a new paradigm in the Indonesian family justice system [37] .

Egypt introduced a more comprehensive divorce restriction system through Law No. 25 of 2019. Husbands are required to undergo pre-divorce counseling and provide reasons acceptable to the court. A 60-day "cooling-off period" was introduced to provide an opportunity for reconciliation. This approach is more systematic than in Indonesia and reflects a serious effort to minimize unilateral divorce.

In Egypt, divorce (ṭalāq) by the husband is still recognized as a right, but it is restricted through administrative requirements such as the obligation to officially register the divorce with the ma'dhūn (marriage registrar) and to notify the wife, as stipulated in Law No. 1/2000. These measures aim to prevent unilateral divorce without clear legal consequences and include mechanisms such as counseling and a cooling-off period to deter impulsive divorces. In Indonesia, the Marriage Law No. 1 of 1974 and the Compilation of Islamic Law further regulate that a husband may only pronounce ṭalāq through a petition to the Religious Court, which examines the grounds for divorce and ensures the resolution of the rights of the wife and children. Both countries, normatively, seek to limit unilateral divorce to uphold justice and family stability, while also supporting the development of inclusive, transparent, and just judicial institutions as outlined in the goals of SDG 16 [39] .

Sue For Divorce (Khulu '/ Divorce on Request Wife)

Divorce is known as the wife's right to file for divorce from her husband through the Religious Court as set up in Law No. 1 of 1974 and the Compilation of Islamic Law (KHI). Reasons for divorce that can be submitted wife include violence, neglect, continuous conflict, or violation of obligation husband. The Religious Court requires the existence of mediation; moreover, first assess whether the reason for divorce is strong enough for processed. In practice, divorce lawsuits in Indonesia are more Lots submitted by the wife, and the judicial approach is directed at protecting the rights of women, including the right to iddah maintenance, mut'ah, and the rights foster child. Procedure for sue divorce is formal and structured, reflecting the state's commitment to protecting the family in a way institutional [40] .

Meanwhile in Egypt, the form of divorce on request wife is known with term khulu ', that is, divorce filed wife with return of dowry (dowry to husband. Khulu ' is arranged in Law no. 1 of 2000, and provides the right to a wife for divorce without having to prove that error husband, enough with the state that he cannot live harmoniously again. However, the wife must give up certain financial rights, such as mahr and mut'ah. The khulu' system in Egypt is an important innovation in Islamic family law because it provides a quicker way out for women, although it is still based on classical fiqh principles. However, khulu' must still be decided through the courts, and in some cases, the judge can encourage mediation before deciding on a divorce.

Based on the above discussion, both legal systems reflect efforts to harmonize the principles of Sharia with the values of substantive justice and non-discrimination, which are essential in building a responsive and gender-just family law system. These efforts also support the realization of a peaceful and just society in line with the objectives of SDG 16.

Legal Status of Children: Children Born during the Iddah Period

Indonesia has undergone a progressive transformation in regulating the status of children through the Constitutional Court Decision No. 46/PUU-VIII/2010, which expanded the recognition of illegitimate children. In the context of children born during the iddah period, the Compilation of Islamic Law provides full recognition of the legal status of the child as a child of the previous husband if the birth occurs within a maximum of 180 days from the marriage or during the iddah period of divorce, by Article 99 of the Compilation of Islamic Law (KHI). This recognition is based on the principle of lineage in Shafi'i fiqh and is maintained to protect children's rights, including inheritance rights and legal identity. In addition, in the practice of religious courts, judges tend to decide the status of children inclusively by considering medical evidence such as DNA and expert testimony. This progressive approach is in line with the values of justice and welfare that are the basis for the transformation of Islamic family law in Indonesia [41] .

In Egypt, the status of a child born during the iddah period is also recognized as a legitimate child of the ex-husband, as long as the birth occurs within a maximum of one year after the divorce or death of the husband, as explained in the Hanafi fiqh, which is the basis of the Egyptian family law system. Egyptian law does not explicitly mention the limits of the iddah period for establishing lineage, but the courts still adopt a classical approach with some flexibility, such as accepting scientific evidence and testimony to establish the father-child relationship (nasab). Although Egypt tends to be conservative, several judicial reforms and fatwas from Al-Azhar show an openness to adapt to modern medical conditions and the protection of children's rights.

Both sets of regulations reflect a harmonization between Sharia principles and the principles of child protection and substantive justice, supporting the development of a responsive, just, and inclusive family law system as mandated by SDG 16.

Inheritance Status: Wajibah Will

In the Islamic family law system in Egypt, the concept of wajibah will was formalized through the -Inheritance Law No. 71/1946 which was amended in 1985, giving special rights to orphan grandchildren (dzawīl arḥam) to receive inheritance through the wajibah will mechanism of a maximum of one-third of the testator's assets, to protect their rights that are hindered by classical fiqh. On the other hand, Indonesia adopted this concept through the Compilation of Islamic Law (KHI) Article 209, but its application is focused on adopted children and adoptive parents, while grandchildren are included in the category of substitute heirs (wilāyah), not as recipients of wajibah wills [42] . Comparative studies show differences in the recipient objects (grandchildren in Egypt vs. adopted children in Indonesia), the method of distribution, and the legal basis. Egypt prioritizes legal reform based on ijtihād and rechtvinding, while Indonesia emphasizes harmonization between sharia, custom, and the value of welfare in the KHI. Despite similarities such as a maximum limit of one-third and a social function to complement deficiencies in inheritance, the two countries still show significant variations in recipient structures, legal provisions, and implementing normative frameworks.

Both countries have adopted these rules as a form of harmonization between Sharia principles and the values of social justice to protect vulnerable groups, as well as to promote the establishment of an inclusive, equitable, and rights-oriented legal system, by the objectives of SDG 16.

In-Depth Analysis. The comparative transformation of Islamic family law in Egypt and Indonesia demonstrates a shared yet distinct trajectory of constitutional ijtihad, where both legal systems integrate Sharia with modern state imperatives and human rights frameworks. Three focal areas-khuluʿ (wife-initiated divorce), the legal status of children born during the iddah period, and the waṣiyyah wājibah (mandatory will)reveal how each country negotiates between classical fiqh and contemporary demands for gender equity and social justice.

In Indonesia, wife-initiated divorce (gugatan cerai) requires legally valid grounds such as violence, neglect, or persistent conflict, as stipulated in Law No. 1 of 1974 and the Compilation of Islamic Law (KHI). The process is evidence-based, includes mandatory mediation, and prioritizes women's post-divorce rights-such as iddah maintenance, mutʿah, and child custody. This structured approach reflects the state's protective role, yet also prolongs resolution. By contrast, Egypt's khuluʿ under Law No. 1 of 2000 allows a wife to dissolve marriage without proving fault, provided she returns the dowry and relinquishes certain financial claims. This expedites proceedings and empowers women's exit from harmful marriages but at the cost of some economic rights. Regarding children born during iddah, both jurisdictions uphold legitimacy to preserve lineage and inheritance rights, though procedural nuances differ. Indonesia's KHI follows Shafiʿi fiqh and Constitutional Court precedents, embracing medical evidence and a more inclusive stance, while Egypt applies Hanafi rules but shows measured openness to scientific proof, signaling gradual doctrinal adaptation.

In inheritance, Egypt's waṣiyyah wājibah extends rights to orphaned grandchildren, correcting gaps in classical law, while Indonesia applies it mainly to adopted children, treating grandchildren as substitute heirs under KHI provisions. The divergence stems from differing fiqh bases-Egypt retaining stricter Hanafi limits, Indonesia using contemporary ijtihad to integrate welfare considerations. Across these domains, both legal systems pursue harmonization of Sharia with the principles of substantive justice, nondiscrimination, and the protection of vulnerable groups, aligning with SDG 16. Yet, their distinct socio-legal contexts, political frameworks, and interpretative traditions yield varied reform paths-Egypt leaning on codified conservatism tempered by selective innovation, and Indonesia blending pluralistic norms with judicial activism to advance family law responsiveness.