Background. The present work focuses on the need to protect prenatal life, which is intricately entwined with delineating the precise biological and legal juncture marking an embryo’s transition into personhood. Drawing upon bioethical insights from domestic frameworks and international jurisprudence, we compare diverse perspectives on the moral and legal standing of the embryo, including its right to life, and invoking legal principles in the context of cellular and regenerative medicine.Aim. The goal of this article is to investigate the various biosafety policy approaches governing embryonic stem cell research, ranging from outright prohibition to authorization solely for therapeutic or scientific ends. Through our analysis, we focus on the unique national context of Brazil to scrutinize the underlying rationale behind a specific legal challenge questioning the constitutionality of the BiosafetyLaw. This law, which permits the utilization of human embryonic cells for research and therapeutic purposes, raises concerns about potential infringement upon the inviolability of the right to life.Methodology. The research is based on deductive reasoning alongside formal-legal methodologies, including textual interpretation and comparative-legal analysis. The research process involved documentary, bibliographic, and virtual analytical inquiries utilizing a variety of resources such as legislative texts, monographs, academic articles, databases, and online libraries. Results. Through our examination in a distinct national context, we delineate the theoretical-philosophical and normative-ethical foundations underpinning the stances of Brazilian Supreme Court justices concerning the utilization of embryonic stem cells. Their arguments predominantly invoked significant constitutional liberties such as freedom of family planning, scientific research, and academic pursuits, intertwined with considerations of human dignity and the sanctity of life. Additionally, some justices cautioned against the potential hazards inherent in genetic manipulation.Implications. The legal and ethical ramifications of Brazil’s approach to biosafety legislation concerning embryo rights invoke the necessity for conducting neutral, unfettered scientific inquiry and regenerative therapies according to specific operational parameters. These include safeguarding the integrity of genetic inheritance, preemptive evaluation of potential risks and benefits (adherence to the precautionary principle), and ensuring informed consent for treatments. A significant hurdle consists in the need to establish robust mechanisms for overseeing research involving human embryos within the domains of biomedicine and regenerative cell therapy