Major breakthroughs in biotechnology are leading to the emergence of novel methods to select and alter future individuals’ genomes. Genetic intervention technology is evolving from the medical practice of screening for life-threatening congenital malformations to the selection against embryos that might develop mild disabilities. Scientific research suggests that heritable genome-editing technology would enable the custom alteration and the enhancement of human biological characteristics, including appearance, athletic and intellectual abilities. These novel developments and their potential long-term impacts raise the question of how effective are the laws on genetic interventions in setting limits to rapidly evolving biotechnologies. This thesis examines genetic intervention laws in the United Kingdom and France and shows it exhibits a pattern of continuous legal changes over the past several years to permit a broadening range of genetic interventions that were previously prohibited. This pattern is characterized by the regulatory licensing of genetic interventions that specific legal restrictions have sought to disallow, such as screening against conditions that are mild, treatable and not predominantly determined by genes. Moreover, governments are currently considering replacing their bans on inheritable human genetic modification with regulations that will allow the alteration of genes linked to conditions deemed “serious” and for “therapeutic” purposes. This proposed regulatory model would enable licensing the very same type of genomic alterations intended to be prohibited – genetic enhancements of human physiological and cognitive capabilities. This legal change pattern is prima facie inconsistent with the key legislative objectives and relevant international instruments, which seek to restrict these particular genetic interventions. The overarching objectives underpinning the restrictions are to prevent a pattern in which the legal boundaries would become gradually laxer, attempts to improve human heredity and the associated human rights, societal and medical impacts. Furthermore, the pattern in which the legal boundaries are becoming laxer over time stems from drawing the lines between permissible and impermissible genetic interventions using language that is vague, subjective and places few limits on the rules’ scope. A law reform can address the current limit-setting challenges by employing clearer conceptual and normative distinctions and by articulating them using language that gives greater attention to clarity, reduced subjectivity, and explicitly delimits the rules’ scope. The thesis offers a blueprint for such a reform, which includes suggestions for specific legislative amendments, clearer conceptual distinctions and newly developed legal tests. The proposed law reform aims to offer a new avenue to advance towards the key policy goal of preventing the misuse of genetic intervention technologies by strengthening its governance.