If the safety and efficacy issues relating to heritable genome editing can be resolved, how should liberal democratic societies regulate the use of this technology by prospective parents who wish to effect edits to the genomes of their prospective children? We suggest that recent developments in South African law can be useful in this regard. The country's apex court recently recognized as a legal principle that the scope of possible reproductive decisions that parents may make when using new reproductive technologies excludes decisions that will cause harm to the prospective child—the principle of procreative non-maleficence. We suggest that the principle of procreative non-maleficence provides a mechanism for striking an equitable balance between two competing interests that are given legal recognition in most liberal democracies: the reproductive rights of prospective parents and the state's duty to protect child welfare.