In embryo research, the "14-day rule" has been considered paramount in ethics research. Regardless of it being a law or guideline in their respective countries, all ethical scientists respect it as a de facto international regulation. However, earlier this year, when the International Society for Stem Cell Research (ISSCR), the world's largest society for academic research on stem cells, published its most updated guidelines, the 14-day rule was no longer included. In a new essay in EMBO reports, ASHBi Assistant Professor and bioethicist Tsutomu Sawai and his colleagues explain the implications of this removal.