When Does an Embryo Become a Human?

Abstract

This study aims to reconstruct the constitutional status of embryos in the era of biotechnology, where in vitro fertilization (IVF), embryo culture, cryopreservation, and embryo research have become commonplace. The current legal order regulates prenatal life in a fragmented manner across different domains. Notably, the Constitutional Court’s 2005헌마346 decision denied the subjecthood of fundamental rights of in vitro embryos prior to implantation and primitive streak formation, adhering to the 14-day rule. However, as technological advancements have enabled research beyond this limit, international research ethics guidelines have reclassified this boundary into an adjustable domain, exposing the rule's nature as a practical compromise. In response, this study proposes the individual continuity of human development—from fertilization to birth—as the core criterion for determining the constitutional status of embryos. By reframing the fertilization theory within the protective framework of human dignity and the right to life under Article 10 of the Constitution, this paper establishes a constitutional baseline for the definition of a human being that remains independent of technological subordination. Furthermore, by defining embryos as provisional and conditional subjects of fundamental rights, this study decouples the recognition of subjecthood from the calibration of protection intensity. It then demonstrates that tiered protection and the balancing of interests are achievable, given the distinct structures of fundamental rights conflicts between in vivo embryos/fetuses and in vitro embryos. Ultimately, this study seeks to present a coherent constitutional baseline regarding the question of 'who is a human being' in the era of biotechnology.