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The 14-day rule for human embryonic research in the UK

23 May 2016
Appeared in BioNews 852

Human embryos can be developed in the laboratory up to 13 days after they were created, recent research has shown (1, 2, and see BioNews 851). This finding has led some commentators to question whether it may be useful to go beyond the 14-day limit for embryonic research in the UK in order to better understand the reasons behind certain forms of miscarriage and infertility or to develop improved embryonic stem cell lines (3, and see BioNews 850).

The 14-day rule was first suggested in the UK in 1984 by the Warnock Report and was then enacted in the UK's Human Fertilisation and Embryology Act 1990. This limit was chosen for a number of reasons including that 14 days is about the stage at which three primitive embryonic layers are formed in the embryo, each one having its own distinct function. It is also believed to be the point at which an embryo can no longer split to form identical twins.

A further reason for this limit was that, when the Warnock Report and the subsequent UK legislation were prepared, the human embryo was not considered to be just a pile of cells. Instead it was assumed to have a certain degree of value and worth reflecting what was suggested to be its 'special status', meaning that some kind of respect could be given.

With the passing of the years, however, this concept of a special moral status of the early embryo has all but been abandoned. Indeed, without any clear definition, the concept was unintelligible, meaningless and bound to be discarded.

In December 2002, Baroness Warnock, admitted that 'I regret that in the original report that led up to the 1990 legislation we used words such as "respect for the embryo" [...] I think that what we meant by the rather foolish expression 'respect' was that the early embryo should never be used frivolously for research purposes,' adding, 'you cannot respectfully pour something down the sink - which is the fate of the embryo after it has been used for research, or if is not going to be used for research or for anything else' (4).

It is difficult to disagree with Baroness Warnock's logic here, since one is challenged to understand any rational basis for the special status.

The UK ethicist, Professor David Jones, in his 22053 article 'The "Special Status" of the Human Embryo in the United Kingdom' explained that rather than engaging with questions of when life or personhood begins, the Warnock Report sought, instead, to go 'straight to the question of how it is right to treat the human embryo' (5).

This means that the Report never tried to be rational or coherent when trying to understand why an entity should or should not be respected. It seems to have misunderstood that the treatment of a being is very much dependent on how it is considered. 

As Jones again explains: 'Warnock's approach thus utterly fails as a convincing account of what it is to respect the moral status of the embryo. Indeed, such an account fails not only to respect the embryo but even to respect the moral feelings of those who respect the embryo.' He then concludes that the way in which the concept of special status is used in the UK debate 'has no inherent content but functions as a mechanism to manage public concerns, so that the issue of the inherent status of the embryo has not been resolved so much as "by-passed"'.

This all points to the fact that one of the main ethical constructions of the Human Fertilisation and Embryology Act 1990 was built on irrational foundations. As a result, it is only to be expected that many should now question the relevance and utility of the special status of the early human embryo, making it also difficult to understand why the 14-day rule should remain.

But the situation would not improve if this 14-day limit was just extended to another later stage. The same challenges with respect to the rationality of the limit would remain. The UK cannot just continue to prohibit what is useless and legalise what becomes useful in embryonic research without any in-depth ethical consideration. Such an approach, based on pragmatism, would be just as irrational and meaningless as the concept of the special status of the human embryo.

9 January 2017 - by Baroness Mary Warnock 
As the Progress Educational Trust's Patron, Baroness Mary Warnock, is made a Companion of Honour in the New Year Honours List 2017, she offers her thoughts on whether the 14-day limit on human embryo research (which she originally proposed in 1984) should be extended...
24 October 2016 - by Anneesa Amjad 
In this podcast, Radiolab presenter Molly Webster explores the origins of the 14-day rule – the internationally agreed two-week time constraint on growing embryos in a lab...
25 July 2016 - by Wendy Suffield 
Should the current 14-day limit for growing human embryos in the lab be extended in light of recent breakthroughs? This was the question posed in the Guardian's Science Weekly podcast following news that embryos have been successfully developed for 13 days...
16 May 2016 - by Dr Helen O'Neill 
Species-specific differences in terms of developmental timing and molecular expression patterns have restricted our true understanding of early human development...
16 May 2016 - by Anneesa Amjad 
An international body representing stem cell scientists has included human genome editing in its updated guidance on the manipulation of stem cells and their use in therapy...
9 May 2016 - by Julianna Photopoulos 
Scientists from the UK and US have grown human embryos in the lab for 13 days after fertilisation – the longest ever recorded. This is beyond the stage when embryos would normally implant in the womb, but just before the 14-day legal limit in the UK...
21 December 2015 - by Wendy Suffield 
At PET's recent conference, Professor Azim Surani claimed that permission to carry out experiments on embryos beyond the 14-day rule could make a huge difference to research. It may be time to review the ethical reasoning behind this time limit...
Comment (User:112519 - 27/05/2016)
With respect, Calum MacKellar's statement that "The UK cannot just continue to prohibit what is useless" is patently absurd: licences cannot be granted unless the proposed research meets one or more of the statutory purposes, none of which is marked "useless enquiry". As useless work cannot be undertaken anyway, there is plainly no need for any "in-depth ethical consideration". It's just as absurd to declare that the UK continues to "legalise what becomes useful in embryonic research" without any "in-depth ethical consideration". As a bioethicist, Dr MacKellar should have been aware that the Nuffield Council on Bioethics issued a press release on 4th May (, announcing its intention to consider the 14 day rule in embryo research, and it is entirely open to others, including the Scottish Council on Human Bioethics, to do the same thing. As to "legalising what becomes useful", Dr MacKellar will be aware that extending the 14 day rule would require the support of Parliament. We should not be surprised if a select committee were to launch an inquiry at some future time, as has happened many times in the past, to help inform Parliamentary debate. Calum MacKellar concedes that the law that emerges from this legislative process is pragmatic, but argues that it is "irrational and meaningless", because the concept of the "special status of the human embryo" fails to "respect the moral status of the embryo" or "the moral feelings of those who respect the embryo". In support of his contention, MacKellar cites Baroness Warnock's comment that "you cannot respectfully pour something down the sink - which is the fate of the embryo after it has been used for research, or if is not going to be used for research or for anything else". Dr MacKellar makes a good point. Nevertheless, I disagree with him that "special status of the human embryo" is "irrational and meaningless." The "special status" concept IS meaningful, because it balances the interests of those with different answers to the "questions of when life or personhood begins". At one end of the spectrum are those who look to empirical facts before reaching moral judgment and who support the use of unwanted and insentient human material for the alleviation of human suffering. At the other are those bound by inflexible Catholic doctrines which hold that life and personhood begin at conception and that suffering is good. The latter are dwindling in number and authority, but their views are still reflected in the ethical oversight and statutory limitations of research involving entities which have not even developed a body. The law is entirely rational. Finally, if the 14-day limit were, to use Dr MacKellar's expression, "just extended" the other provisions of the Human Fertilisation and Embryology Act would remain in place. "In-depth ethical consideration" would in consequence be an integral part of the licence approval process anyway.
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