What is the significance of sex characteristics and gender identity in public law? Why are these personal attributes important for the legal relationship between the person and public authorities? What happens when people do not conform to the assumptions about sexual anatomy and gender identity that are presupposed in the law? Gender Diversity in Public Law explores these questions through an extensive analysis of jurisdictions across Europe, Latin America, and Asia. By integrating comparative law with gender and constitutional studies, the volume examines how gender diversity is both recognized and regulated in different legal systems. This book shows that sex characteristics and gender identity are central to public law. It demonstrates that legal systems are not based solely on the existence of men and women. Instead, they rely on the presence of men, women, and nonbinary individuals, each characterized by specific physical and identity traits. When people exhibit sex characteristics and/or a gender identity that defy legal assumptions and definitions, public law intervenes and actively shapes the subjects it requires. At the same time, legal systems are gradually becoming more inclusive of gender diversity, and this book investigates how emerging models of recognition are transforming public law to recognize gender-diverse people. Gender Diversity in Public Law offers a comparative perspective on the complex relationship between gender diversity and public law, shedding light on a crucial aspect of this field-one that has remained largely understudied until now.