Extracts from Lord Sumption’s speech.

“[this speech] provides a convenient occasion to say something about the advantages and disadvantages of specialisation. Like any body of specialists, the family bar and the solicitors with whom they work are a great depository of knowledge and experience. In a field where most decisions are essentially discretionary, specialised knowledge and experience are more than usually valuable. Yet even by the standards of legal specialists, family law seems usually self-contained to an outsider… To me this all seems rather surprising. Admittedly, I come to this question with a certain amount of baggage. I have always taken the view that legal specialisations are essentially bogus. At the bar, I liked to trespass on other people’s cabbage patches. As a judge I do it most of the time…
But there have been two occasions in my professional life when I have been shaken in my view that it is all just law. One was my only foray, as Counsel, into patent litigation. I will not trouble you with this unhappy story. It persuaded me that chemical patents at least were a remote juridical island, best left to its savage inhabitants. The other occasion was when I started reading up in preparation my first encounter with family law in the Supreme Court. The case was Prest v Petrodel Resources [2013] 2 AC 415…I suggested in my own judgment that,
“courts exercising family jurisdiction do not occupy a desert island in which general legal concepts are suspended or mean something different.”
The principle that there are no desert islands in the law seems to me to be a valuable one, which applies well beyond the realm of family law. The essential reason why I am sceptical of specialisation is that I do not regard law as comprising distinct bundles of rules, one for each area of human affairs. This is partly because no area of law is completely self-contained. Family law, like (other kinds of law)… has to be applied to a variety of different kinds of property and other legal rights. These have their own legal characteristics, which do not always lend themselves to the ends of justice as a family judge would see them…
There is, however, a …fundamental reason for deprecating an excessively specialised approach. Law is, or at least should be, a coherent system. Of course, different human problems pose their own peculiar challenges, which the law must accommodate. But these challenges are 3 not always as peculiar as people think. The practice of law, whether by judges or advocates, involves applying a range of common techniques and common instincts to a variety of legal problems.
The common techniques are the objective construction of legislation and other written instruments, a respect for the body of decided case-law, and a sensitivity to changing attitudes in the world outside the law.
The common instincts are those of the common law, which are essentially libertarian. They are founded on respect for the autonomy of the individual, a rejection of abstract moral duties unless traceable to some particular relationship or status, and a distrust of prescriptive rules without a clear social justification. These instincts operate within broad limits determined by our most basic collective ethical and moral values, in other words by public policy.
The late Ronald Dworkin, in the last book that he wrote before his death, observed that truth is not only coherent but mutually supporting. What we think about any moral or legal issue must be able to stand up to any argument we find compelling about any other. The erection of impenetrable partitions between different areas of law obstructs this process. It is the fastest route to incoherence that I know. …

.. The Court in Radmacher was influenced not just by the approach of the common law, but by the attitude of other jurisdictions whose social values seemed to be similar to our own. The social and financial autonomy of the great majority of modern women in western societies may well lead to more convergence with the libertarian traditions of the common law. The law’s approach to children has moved in the opposite direction, as the growing public perception of their vulnerability feeds into legislation and judicial attitudes. But even there, the law uses its parental authority to impose what are essentially libertarian solutions. In his penetrating judgment in Re G (Children) [2013] FLR 677, Sir James Munby has equated the welfare of children with “an essentially Aristotelian notion of the ‘good life’”. Like Aristotle, he thought that the essence of the good life lay in personal self-fulfilment. Personally, I think that he was right about this. But it is a very humanist, a very individualist, and a very western view. Important sections of our society do not share it, including much of the Islamic and Orthodox Jewish communities and the spiritual end of the green movement. The orders that he made in that case for the education of the children were overtly designed to give them the widest possible range of autonomous choices about their own way of life, although in the eyes of the Hassidic community from which they came the very purpose of education was to limit their choices to what was thought to be acceptable to the Almighty.
One of the problems of specialisation is that it encourages a view of one’s subject which is too self-contained. We do not have to resort to Aristotle for a solution to our problems, but we can at least look into the garden next-door. In my experience, with a few notable exceptions, judges and advocates rarely search for principle beyond their own areas of specialised expertise. Advocates come into court with a library of familiar authorities which are part of the vernacular of practice in their area, without trying to relate them to any more fundamental legal principles. They take for granted rules of law which sometimes strike outsiders as distinctly odd but are too familiar to have struck practitioners that way. In the Supreme Court this is particularly problematic. We deal mainly with cases where the existing authorities are inconclusive, unsatisfactory, out of date or non-existent.
One of the advantages of an appellate system is that it allows decisions from a specialised jurisdiction to be reviewed from the outside, “at a distance” if I may echo the title of this address. There will usually be at least one specialist on the appeal panel, both in the Court of Appeal and the Supreme Court. But his or her voice will not necessarily be decisive. The proposition has to run the gauntlet of external scrutiny. This permits a measure of cross-fertilisation between different areas of law, which for my part I think profoundly healthy. This is not of course a phenomenon peculiar to family law. In the last half-century the law of contract has been significantly influenced by concepts derived from public law. The concept of property in private law has been fundamentally affected by human rights law. The law of securities and the law of restitution have been transformed by a much wider resort to equitable principles than would have been conceivable a generation ago. The rules for construing patents and deeds, which were once a law unto themselves, have now been more or less integrated into the general body of principle governing the construction of written instruments. …Ultimately all of this depends on a willingness on the part of practitioners working in their core areas to look critically at familiar principles and relate them to what is happening elsewhere. Sometimes, distance lends enchantment…”

Edited and formatted for ease of reading. This speech is available on the Supreme Court website https://www.supremecourt.uk/