The '14-day rule' is a part of the Human Fertilisation and Embryology Act 1990 which makes it a criminal offence to keep a human embryo alive in the laboratory for longer than 14 days from fertilisation. This limit was originally recommended by a government committee I chaired - the Committee of Inquiry into Human Fertilisation and Embryology – in a report we published in 1984.
The 1990 Act was a brand new piece of legislation, since before 1978 there had never been a baby born from an embryo developed outside the womb. Our committee was set up by government to advise ministers on whether IVF should be permitted at all, and – if so – then how it should be regulated. They, and we, were very much aware that we had to break new ground and we had no precedents to guide us.
Luckily we did have guides, in the shape of Jeremy Metters (an excellent scientific civil servant who later worked as an adviser on European law in the same field) and the late Anne McLaren (a leading figure in developmental biology who was then director of the Medical Research Council's Mammalian Development Unit). We could not have produced our report without these two people. There were two obstetricians on the committee, but only one of them knew much about embryonic development.
It took our committee very little time to decide that we would recommend that IVF be allowed to continue, but subject to regulation which should have legal status. This meant law, and law needs certainty.
We could have recommended that the limit after which an embryo could not be kept alive in vitro should be determined by its stage of development. If we had done this, and if such a law had been passed, then if someone were accused of keeping an embryo alive too long the defence might be that this embryo was developing in an exceptional way or unusually slowly. Each case would have to be investigated separately, and the investigation would require considerable expertise.
But everyone can count up to 14, and everyone can keep and examine records. The first of our recommendations was the establishment of a regulator – the HFEA, which exists to this day – whose legal duty of inspection includes ensuring that records are unambiguous.
Some people have criticised the 14-day limit on the grounds that it is arbitrary and therefore irrational. The charge of arbitrariness is partly justified. We did pick on a number of days, after which we understood that the embryo began to develop more swiftly towards becoming a curled-up fetus with a spinal cord and a central nervous system.
The number 14 was not arbitrary in the sense that we drew it out of a hat. But it was arbitrary in the sense that it might have been a different number, though not very greatly different. At any rate, a workable law demanded a degree of invariability.
I am persuaded by scientists who work in this field of research that a surprising amount could be discovered, of both theoretical and practical importance to the understanding of early embryonic development, if the rule were changed by as little as two or three days (let alone the week or more that some people want).
It must be remembered, however, that until 2016 – when an embryo was destroyed at 13 days, in order to comply with the law – no one had ever kept an embryo alive in vitro for more than nine days. For the most part, embryos had been kept alive in vitro for only three to five days.
Reluctantly, I suggest that researchers should now take more time to fully exploit the extra days right up to the 14-day limit, before arguing for the legal limit to be extended. I am not particularly proud of my timidity. It has nothing to do with science, and everything to do with politics.
When the 1990 Act was introduced, the opposition to any sort of research using human embryos was vociferous. There has been similar opposition every time the Act has been amended, or new Bills have been introduced that deal with the same sort of topic. The basis of the opposition is usually the so-called slippery slope argument, which has predominated even among those who also have religious scruples about using embryos for research and then destroying them.
Objectors have relied on a means of persuasion recognised by Aristotle in his Rhetoric, namely the argument that what has happened in the past will happen again. It was argued when the 1990 Act was introduced that if a number of days is specified after which it is unlawful to keep an embryo alive in the laboratory, then this limit will soon come to be disregarded and will become a dead letter, and that this had happened previously with late abortions.
Aristotle noted in his Rhetoric that if it is to be argued effectively that what has happened in the past will happen again, the analogy between the past and the present must be strong. Although many people who oppose abortion also oppose research using human embryos, the analogy between the two is not strong. In the case of late abortions, specific exceptions of human necessity can be properly adduced to justify the breach of the limits set. The same cannot be said of extending the life of an embryo in vitro beyond 14 days.
The argument from analogy of a slippery slope has often been adduced, but has not prevailed. One might think that the length of time that has passed since the 1990 Act reached the statute book, and the fact that most European countries have now taken the same line as was recommended by our committee (setting a limit of 14 days), have weakened the objectors' case.
But their case is in one way now more plausible than it was at the beginning. For they can now argue (though of course not prove) that the 14-day rule has remained intact simply because no researcher had the technique needed to keep an embryo alive for so long, and that now such a technique has been discovered, the rush down the slippery slope will follow.
I have the sense that pro-life people, who do not seem to realise how intensely pro-life IVF itself has always been, are waiting in the wings and marshalling their forces to make an assault on what they regard as immoral legislation all over again. They will say: 'We always knew that the slippery slope would prove itself, and here it is, just as we said.'
This is the reason why I want the 14-day rule to remain in place, at least for the time being. Perhaps with the 14-day rule we erred on the side of caution. But you cannot successfully block a slippery slope except by a fixed and invariable obstacle, which is what the 14-day rule provided.
If there is to be a change, it cannot be introduced entirely on the evidence of science. The suspicion that scientists will go to any lengths to increase knowledge, regardless of morality or social good, goes very deep – perhaps especially in Parliament.
IVF and stem cell research would never have been permitted, if ideas had come from scientists alone. It was necessary to set up the whole apparatus of an independent Committee of Inquiry, with many non-scientists among its members and taking evidence from many non-scientific bodies, before Parliament could be persuaded to legislate.
I fear that something as elaborate as this would be needed to get the 14-day rule changed. The risk would be that all the progress we have made since 1990 would be lost.