Conducting research on embryos beyond 14 days’ gestation is against the law in 12 countries, including the United Kingdom; the U.S. has only “guidelines” recommending the 14-day limit. Now researchers and others are pushing against that limit. They find it too confining. Where did this rule/guideline originate?

Louise Joy Brown, the world’s first “test-tube baby,” was born 25 July 1978. She was the product of her mother’s egg, fertilized by her father’s sperm in vitro (in glass), through the combined efforts of physiologist Robert G. Edwards and OB/Gyn Patrick Steptoe.  After her birth was announced, Parliament appointed a committee, headed by ethicist Mary Warnock, to advise that legislative body regarding the new assisted reproductive technology. It was the Warnock Committee who authored the 14-day rule in Britain.

How did the Warnock Committee arrive at the 14-day rule?  Here is their reasoning:

…the question was not, as is often suggested, whether the embryo was alive and human, or whether, if implanted, it might eventually become a full human being. We conceded that all these things were true. We nevertheless argued that, in practical terms, a collection of four or sixteen cells was so different from a full human being, from a new human baby or a fully formed human foetus, that it might quite legitimately be treated differently. Specifically we argued that, unlike a full human being, it might legitimately be used as a means to an end that was good for other humans, both now and in the future.

…If, on broadly utilitarian grounds, the benefits from the use of embryos at this stage seemed very great, and if not only was there no harm in the sense of immediately felt pain to the embryo but also in addition there were no absolute outrage of general moral sentiment…then the majority argued that the embryo might be used for research. The precise point of dispute within the committee was not on the value that should be attached to human life in general, but to the value that should be attached to human life at its very earliest stage of development. It was here that it was necessary to invoke the law….Therefore there must be a law so drafted as to provide a definition of “very early.” We recommended…a limit of 14 days. The point was not however the exact number of days chosen, but the absolute necessity for there being a limit set on the use of embryos, in terms of a number of days from fertilization. In this way the law would be clear. Mary Warnock, A Question of Life: The Warnock Report on Human Fertilisation & Embryology (Oxford, UK: Basil Blackwell, 1985), xiv-xv.

The Warnock Committee—a slim majority, not unanimously—decided that because the embryo did not look very human, research could be done on it.  “Until when?” was the next question.  The Royal College of Obstetricians and Gynaecologists proposed the limit of 17 days because that is the beginning of early neural development. The British Medical Association favored 14 days, although the Royal College of Physicians and the Medical Research Council recommended the “end of the implantation stage” as a reasonable limit (Warnock, p. 65). Fourteen days – before the primitive streak signaling an individual (and not twins) developing – was chosen as the limit; Parliament approved; and such has been the case since that time.
Now, because of technological changes, embryos can be cultured in the lab longer than two weeks, and because through synthetic biology, organisms resembling embryos beyond the 14-day mark can be produced, the 14-day rule is seen as a moveable post.  Sarah Chan, in “How to Rethink the Fourteen-Day Rule,” writes

The fourteen-day rule, by contrast, was not a moral bright line. Ideas about individuation at the formation of the primitive streak (after which twinning is no longer possible) plus the absence up to that point of any structures associated with sentience, added weight to the argument for selecting that limit. Nonetheless, the rule was not meant to imply that human embryos had no moral status before fourteen days and suddenly acquired full moral status afterward. In fact, embryo research policy cannot be interpreted as expressing a definitive position on moral status at all; instead, it recognizes the embryo as the subject of considerable societal concern without ever resolving the question of moral status. Therefore, the rule itself was never a direct transposition of moral principle into policy.

The Warnock Committee did not find it necessary to speak to exactly what the embryo is, but did find themselves capable of telling people what was permissible to do with it. Sarah Chan would have us follow blindly in those footsteps. A better proposal is to evaluate the embryo not for what – but who – it is. In response to the Warnock Committee, Nigel Cameron said it very well:

If it is true …that the only way in which we can make sense of the human embryo is to regard it for moral purposes as the human being the biologist has already found it to be, the question of embryo research is the ultimate question man faces as he considers his relations with his fellows. That is, the question of embryo research…becomes…the old question of the propriety of the experimental use of human subjects.  The human embryo ceases to be ‘human material’ deserving of some special category of respect, and becomes instead ‘one of us,’ a human existence, the life of a fellow-member of our own species.  The morality of embryo research is therefore the morality of all human research. And there has long been a consensus that involuntary research that may harm and cannot benefit its human subject is ethically indefensible. Nigel M. deS. Cameron, Embryos and Ethics, ed. Nigel M. deS. Cameron (Edinburgh: Rutherford House, 1987), 5.

Our way forward will be clearer when we come to see the embryo, at whatever age, as “one of us.”