Authored By: Mpho Cynthia Raat
University of Fort Hare
Abstract
This article examines the intersection of customary international law (CIL) and gender rights assessing how unwritten legal norms have influenced global gender equality. While Customary international law plays an important role in shaping binding obligations, its application to gender issues has often been inconsistent. Through an analysis of key legal frameworks, case laws, and critical evaluations, this article explores how customary international law addresses gender discrimination and women’s rights. Additionally, it also evaluates recent developments and proposes a way forward for ensuring that gender justice is better reflected in customary norms. The paper argues for a more inclusive and progressive interpretation of CIL to bridge the gap between theory and practice.
Introduction
The customary international law, also known as international custom, refers to rules that arise from the consistent and general practice of states, which they follow out of a sense of legal obligation (opinio juris).[1] This means that even if these rules are not written in treaties or formal legal texts, they are still considered legally binding when followed by states as part of accepted international practice.[2] According to Article 38(1)(b) of the Statute of the International Court of Justice, international custom is recognized as a source of law when it serves as evidence of a general practice accepted as law. Therefore, customary international law is supported by article 38(1) (b) of the Statute of the International Court of Justice as the source.
In recent years, the relationship between customary international law and gender justice has become increasingly important. While treaties such as the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW) and the Universal Declaration of Human Rights (UDHR) have played a major role in promoting women’s rights, the development of customary rules protecting gender equality has been slower and less consistent.[3] This raises important questions about how unwritten international norms can support or hinder progress toward eliminating gender-based discrimination, especially in countries where treaty implementation is weak or absent.
In the current legal scenario where global movements such as #MeToo, discussions on reproductive rights, and gender-based violence are at the forefront there is an urgent need to examine how customary international law can evolve to better support women’s rights and gender equality worldwide.[4] This article focuses on the role of customary international law in advancing gender justice, Gender Rights in Customary International Law, Judicial Interpretation: Case Law and Customary Norms, Gaps and Challenges in Customary Gender Norms, Recent Developments and suggest ways forward to ensure that gender-sensitive norms are more effectively reflected in international custom.
Legal Framework: Gender Rights in Customary International Law
The customary international law is formed through the consistent practice of states accompanied by the belief that such practice is legally required (opinio juris). Although many gender rights are codified in international treaties like the Convention on the Elimination of All Forms of Discrimination Against Women (CEDAW) and the Universal Declaration of Human Rights (UDHR), some gender protections have also emerged through customary norms.[5] For example, the prohibition of sexual violence during armed conflict has become widely accepted as customary law. Additionally, the principles of non-discrimination and equality before the law enshrined in many national constitutions and international instruments have contributed to shaping customary norms on gender rights. While treaties provide a clear legal framework, their influence on customary law depends on widespread and consistent state practice and acceptance.
Judicial Interpretation: Case Law and Customary Norms
The International criminal tribunals have contributed to the recognition of gender-based crimes under customary international law. In the case of Prosecutor v. Akayesu[6] the tribunal recognized rape as an act of genocide, marking a milestone for gender justice in international law. This landmark judgment was a turning point for gender justice in international law and helped confirm that sexual violence during armed conflict could amount to genocide and thus be prohibited under customary international law. Similarly, the case of Prosecutor v. Kunarac[7] (2001) classified rape and sexual slavery as crimes against humanity, establishing that such crimes are prohibited under customary international law. This case was crucial in confirming that such gender-based crimes are not only violations of human dignity but also violations of norms that have attained customary international law status. These rulings underscore the evolution of gender-based crimes from being seen as collateral wartime abuses to universally condemned and legally binding offenses under international custom.
Critical Analysis: Gaps and Challenges in Customary Gender Norms
The customary international law’s protection of gender rights faces significant challenges. Many customary norms remain broad and fail to address specific gender-related issues such as reproductive rights or domestic violence.[8] Furthermore, patriarchal attitudes in many states mean that discriminatory laws and social practices persist, preventing the formation of progressive customary norms. Another challenge is the inconsistent expression of opinio juris by states; often, states act in ways that support gender equality but do not explicitly recognize these actions as legal obligations. [9]Lastly, the development of customary norms often excludes marginalized groups, including women from the Global South and minority communities, which limits the universality and fairness of these norms.[10]
Recent Developments
In recent years the have been an important development that may strengthen the role of customary international law in gender justice. According to the UN Security Council’s Women, Peace, and Security (WPS) Resolutions, particularly Resolution 1325 it provides for the important role of women in the prevention and resolution of conflicts, peace negotiations, peacebuilding, peacekeeping, humanitarian response and in post-conflict reconstruction and the importance of their equal participation and full involvement in all efforts for the maintenance and promotion of peace and security.[11]
According to the Rome Statute of the International Criminal Court, which criminalizes gender-based crimes such as rape, sexual slavery, enforced prostitution and other forms of sexual violence as war crimes and crimes against humanity.[12] This codification plays a key role in influencing customary international law by setting clear legal standards that many states have adopted in practice, even outside the International Criminal Court system.
The scholars and legal practitioners increasingly debate whether gender equality is evolving into a jus cogens norm a peremptory norm of international law from which no derogation is permitted. [13]If recognized as such, gender equality would hold the highest status in international law, overriding any conflicting treaties, customary rules, or national laws. This would significantly strengthen legal obligations on states to respect and uphold gender rights in all circumstances.[14] While these developments suggest a growing international consensus on the importance of gender equality, its full incorporation into customary international law remains incomplete. Achieving this status requires not only widespread and consistent state practice but also a clear expression of opinio juris that is, the recognition by states that upholding gender equality is a legal obligation, not merely a political or moral choice.[15]
Suggestions / Way Forward
In order to strengthen the role of customary international law in promoting gender justice, a number of practical steps can be taken by states, international bodies, and civil society. First, gender-sensitive norms should be codified more clearly in UN declarations and resolutions, which, while not binding themselves, can shape state behaviour into customary norms. This would help fill the gaps left by vague or general rules.
Second, it is essential to increase the representation of women and marginalized gender groups in international decision-making bodies, such as the International Court of Justice, UN treaty bodies, and other legal institutions. Their perspectives are critical in shaping inclusive and equitable customary norms.
Third, states must demonstrate opinio juris by not only practicing gender equality but also publicly affirming that such practices are part of their legal obligations. This would reinforce the legal foundation needed for the evolution of gender-sensitive custom.
Fourth, strategic litigation in international and regional courts should be encouraged to establish precedents and build legal recognition of gender rights. Such cases can push the boundaries of what is considered customary, especially in areas like reproductive rights, domestic violence, and economic participation.
Lastly, civil society organizations and academics should continue documenting state practices and engaging with legal mechanisms to hold governments accountable. Their advocacy can influence international opinion and ultimately help shape customary law in favour of gender equality.
Conclusion
Customary international law holds significant potential for advancing gender justice globally. While it currently plays a limited role compared to treaty law, it remains a powerful source of binding obligations, especially in states where formal agreements have not been adopted or enforced. The recognition of gender-based crimes in international criminal law, along with UN initiatives and global advocacy movements, shows that gender rights are increasingly influencing customary norms.
However, to close the gap between theory and practice, customary international law must evolve more deliberately to reflect the realities and needs of women and marginalized gender groups. This requires active efforts by states, courts, and civil society to develop and support norms that promote equality, dignity, and protection for all. Strengthening customary international law with a gender perspective is not only a legal necessity but also a moral imperative in the pursuit of universal human rights.
Bibliography
Convention on the Elimination of All Forms of Discrimination Against Women, Dec. 18, 1979, 1249 U.N.T.S. 13.
Universal Declaration of Human Rights, G.A. Res. 217A (III), U.N. Doc. A/RES/3/217A (Dec. 10, 1948).
Prosecutor v. Akayesu, Case No. ICTR-96-4-T, Judgment (Int’l Crim. Trib. for Rwanda Sept. 2, 1998).
Prosecutor v. Kunarac, Case Nos. IT-96-23-T & IT-96-23/1-T, Judgment (Int’l Crim. Trib. for the Former Yugoslavia Feb. 22, 2001).
Rome Statute of the International Criminal Court, July 17, 1998, 2187 U.N.T.S. 90.
S.C. Res. 1325, U.N. SCOR, 55th Sess., U.N. Doc. S/RES/1325 (Oct. 31, 2000).
Statute of the International Court of Justice, art. 38(1)(b), June 26, 1945, 59 Stat. 1031, T.S. No. 993.
Michael Scharf, Customary International Law, 20 ILSA J. Int’l & Comp. L. 305 (2014).
Lena Holzer, After #MeToo: Law, Justice and Sexual Violence: Introduction to the Special Issue, 32 Soc. & Legal Stud. 137 (2024), https://doi.org/10.1177/0964663924125678.
Jonathan Wampler, Jus Cogens and the Lack of a Universal Gender Equality Norm, Oxford Human Rights Hub (June 15, 2023), https://ohrh.law.ox.ac.uk/jus-cogens-and-the-lack-of-a-universal-gender-equality-norm.
[1] Michael Customary International Law 20 ILSA J. Int’l & Comp. L.: Volume 20 of the ILSA Journal of International & Comparative Law 305 (2014).
[2] Ibid.
[3] Statute of the International Court of Justice art. 38(1)(b), June 26, 1945, 59 Stat. 1031, T.S. No. 993
[4] Lena, After #MeToo: Law, Justice and Sexual Violence: Introduction to the Special Issue, 32 137 (2024).
[5] Convention on the Elimination of All Forms of Discrimination Against Women, Dec. 18, 1979, 1249 U.N.T.S. 13; Universal Declaration of Human Rights, G.A. Res. 217A (III), U.N. Doc. A/RES/3/217A (Dec. 10, 1948).
[6] Prosecutor v. Akayesu Case No. ICTR-96-4-T, Judgment (Int’l Crim. Trib. for Rwanda Sept. 2, 1998).
[7] Prosecutor v. Kunarac Case Nos. IT-96-23-T & IT-96-23/1-T, Judgment (Int’l Crim. Trib. for the Former Yugoslavia Feb. 22, 2001).
[8] Catherine ‘`International gender equality norms and their fragmented protection in conflict’’ Vol 9, No 1 (2019).
[9] Catherine ‘`International gender equality norms and their fragmented protection in conflict’’ Vol 9, No 1 (2019).
[10] Ibid.
[11] S.C. Res. 1325, U.N. SCOR, 55th Sess., U.N. Doc. S/RES/1325 (Oct. 31, 2000).
[12] Rome Statute of the International Criminal Court, July 17, 1998, 2187 U.N.T.S. 90.
[13] Jonathan Wampler, Jus Cogens and the Lack of a Universal Gender Equality Norm, OXF. HUM. RTS. HUB June 15, 2023.
[14] Ibid.
[15] Jonathan Wampler, Jus Cogens and the Lack of a Universal Gender Equality Norm, OXF. HUM. RTS. HUB June 15, 2023.
