This case study deals with the regulation of human embryonic stem-cell (hESC) research in Brazil. It aims to analyze the process that led to the authorization, in 2005, of the use of stem cells obtained from so-called supernumerary embryos for purposes of research and therapy. We argue that the pro-research lobby in Brazil had considerable success because it framed the issue by referring to Brazil’s peculiar policy background in the fields of assisted reproduction and embryo research. Moreover, this group of actors strategically avoided associating hESC research with abortion, highlighting the humanitarian aspects of this kind of research, rather than the motto of freedom of scientific research. Finally, it was able to rely on the judgment of a fairly progressive Supreme Court, which was also sensitive to public opinion at a time of ‘court activism’ or the ‘judicialization of politics’ in Brazil.