So how - if at all - would this have changed things for Natallie Evans? If her partner had opted to relinquish control to her, she could have implanted her embryos. But why would he choose to do so? If a man has misgivings about the idea of parenthood at this stage, his doubts will not be resolved by relinquishing his right to be involved in all future decisions relating to the embryos.
But perhaps this option might at least flush the reluctant partners out of the woodwork. If Mr Johnston had been offered the chance to cede control of the embryos to Ms Evans, and had refused, she might have become aware much earlier of the fact that he was not fully committed. She could then have considered saving some of her eggs to be fertilised with donor sperm so that if Mr Johnston did withdraw his consent, she would still have some chance of having a child with her own eggs.
However, there are a number of difficulties here. Firstly, if there are very few eggs available it may not be feasible to hedge one's bets in this way. Secondly, one might fail to recognise the 'warning' implied by the spouse or partner's refusal to cede control of the embryos. Thirdly, donor gametes are in short supply, so there may be complications if a delay is required, since eggs cannot easily be frozen.
The fourth - and perhaps most significant - flaw in this proposal is the question of whether such an agreement could really be treated as binding. Choosing to become a parent is a momentous and significant event that affects some of the most deeply-held values that people can have. Sozou, Hartshorne and Sheldon suggest that we shouldn't attempt to protect individuals by preventing them from signing away these choices, as this would be unduly paternalistic. But even if we agree that paternalism is not warranted, problems will arise if individuals change their minds.
In such cases, the enforcement of the law might seem just as problematic as it was for Natallie Evans. Relinquishment of embryos at an early stage might be bitterly regretted later on. Circumstances may change in ways that were not foreseen at the outset. A man who has allowed embryos to be created with his sperm five years ago may feel very differently about the prospect of their being used, for example after he has married someone else and had children with her. A man who relinquishes his rights over embryos created with his sperm could argue compellingly that he was not - and could not reasonably have been - aware of how he would feel when the time came. This might undermine the ethical if not the legal validity of consent given in such circumstances.
One can foresee, if this were made law, that some men might try to rescind their agreement, or dispute the terms under which the original contract were drawn up. This in turn would place more pressure on the consent process itself, and on the staff who usher patients through this process. The authors suggest that clinics already provide good consent procedures for patients, so the adoption of this new legislation would only add a small amount of extra work.
However, anecdotal evidence suggests otherwise. Patients are often rushed through the consent process by staff who are busy and unable to spell out every possibility to patients. Patients are often bewildered, intimidated, or simply distracted. (In Ms Evans' case, consent forms were being signed just after she had been told of her cancer diagnosis). In this less than perfect world, there is ample scope for sloppy or inadequate briefing, which may undermine the validity of consent.
Such complaints might have limited legal strength, but the emotive appeal could be just as powerful as that of Natallie Evans' situation. What's more, the man in this situation suffers on two fronts. Not only are his reproductive wishes thwarted, he is also potentially faced with a legal obligation to support the offspring whose creation he opposes. The justice of enforcing a long term financial burden on the basis of an agreement that may have been made years before, and in circumstances which have altogether altered, seems highly dubious.
The authors do not explicitly discuss this issue; it may be that they assume financial responsibility would also be signed away. But without specifically assuring this, their proposed changes to the consent arrangements are problematic.
Ms Evans received a great deal of public sympathy, hence the view that the law should change. But the change proposed by Sozou, Hartshorne and Sheldon simply creates new potential objects of sympathy: the men who sign away their rights and may later regret doing so. It is not obvious why this is any better than the original situation. Given the issue about financial maintenance, it could be argued that it is worse. The existing law in this area is not perfect, but the suggested changes look distinctly unpromising, unless accompanied by a much more sweeping overhaul of the law in this area.
A woman who wishes her partner to relinquish his legal rights over jointly-created embryos would perhaps be better off seeking a bona fide sperm donor, whose rights and responsibilities are clearly set out in law. And a man who would commit himself in advance to an agreement of the kind set out in this proposal would have to be extraordinarily virtuous... or perhaps simply foolish.