As expected, last month the International Society for Stem Cell Research (ISSCR) updated its guidelines for stem cell research. The marquee guideline is the relaxation of the limit of 14 days on how long a human embryo may be kept alive in a lab.

According to the ISSCR the update reflects emerging advances including stem cell-based embryo models, human embryo research, chimeras, organoids, genome editing and ectogenesis.

Even though these recommendations do not have the force of law, they are very influential and pressure will mount in key countries like the UK, the US and Australia to amend or abolish the 14-day rule. Bioethicists have been calling for a revision in a number of journals over the past few years. In this article David Albert Jones and Michael Wee of the Anscombe Centre for Bioethics, in the UK, comment on this development.


When the UK legalised experimentation on human embryos in 1990, it was promised that this would be subject to various “safeguards”:

(1) No human embryo would be created by cloning;

(2) No human embryo would be genetically modified;

(3) No part-human, part-nonhuman embryo could be created;

4) The use of human embryos in assisted reproduction and in research would be regulated with the utmost care;

(5) And, most famously, no experimentation on human embryos would be permitted after 14 days.

The first three of these “safeguards” have since been stripped away by various acts of law (see Fig. 1). With regard to the fourth “safeguard”, the Human Fertilisation and Embryology Authority (HFEA) has rarely, if ever, refused to grant or to extend a research licence.

Nonetheless, to this day, the 14-day rule on experimentation has survived, though not out of principle, but simply because until recently scientists had been unable to culture a human embryo for more than 13 days. In effect, the rule has been like a speed limit that no car could physically achieve. It was a vacuous prohibition, forbidding the impossible and allowing experimentation on human embryos at every stage that this was physically possible.

Now that scientists have finally reached this limit – which means the 14-day rule has actually become a real prohibition, and might prevent some human embryos from being experimented on – advocates of embryo experimentation are calling for this limit to be extended.

Four years ago, in the United Kingdom, some had started to call for the 14-day rule to be extended to 28 days. Yet this would clearly be mere lip service to the need for ethical restraints. Could anyone believe that the 28-day rule would stay in place, if the 14-day rule was to be amended to accommodate new technological developments? It did not happen.

However, now the International Society for Stem Cell Research, an international organisation in which British scientists play a significant role, has revised its research guidelines. It has abandoned the 14- day rule altogether and placed no time limit on culturing human embryos.

These new proposals constitute a rule on embryo experimentation that is, in effect, a shifting goalpost. Considering that abortion is legal up to 24 weeks in Britain, or up to birth for babies with disabilities, one must wonder what principle would protect unborn infants from experimentation up to, or beyond, these same limits.

Unfortunately, pragmatism combined with the belief that the ability to do more is always progress does not provide a solid foundation for doing so. Once the 14-day rule falls away, the only real limit, it seems, to experimentation would be the scientific limit as to how long embryonic or foetal human beings can be sustained outside the womb – or, indeed, in an artificial womb (ectogenesis).

Rather than provoking calls to extend the legal limit in the United Kingdom, the development on culturing embryos beyond 13 days should give us pause to consider whether more permissive rules on embryo experimentation will lead to increasingly cavalier attitudes towards human life.

The HFEA does not provide annual figures on the number of human embryos destroyed during or after experimentation, but figures released in 2007 give some indication of the death toll (see Fig 2).

The further the limits of research are pushed, the more scientists will be confronted with research subjects that look more recognisably human. To experiment on human embryos that are up to 14-days-old – extremely vulnerable human lives – is already a grave injustice and a form of exploitation. Extending the 14-day rule would make more embryos vulnerable to exploitation and strip away one of the few remaining limits to injustices committed against embryonic human beings.

Professor David Albert Jones is Director of the Anscombe Bioethics Centre, Oxford; he was appointed in 2010. He is also a Research Fellow at Blackfriars Hall, Oxford University and Professor of Bioethics...

Michael Wee

Michael Wee is the Education and Research Officer at the Anscombe Bioethics Centre. He is also an Associate Member of the Aquinas Institute, Blackfriars Hall, Oxford; Associate Lecturer in bioethics at...