Foreword to "Enrichment at the Claimant's Expense Attribution Rules in Unjust Enrichment"
(Eli Bail, Hart Publishing, December 2016)
Foreword by Justice Edelman
The immediate impression of doctrinal private law in most countries outside the United States is of an intensely conservative, highly technical tradition bound by rules. This private law tradition dates back two millennia. At that time, one of the greatest Roman jurists noticed the existence of obligations outside contract and tort. This jurist, about whom we know little more than his (common) name Gaius, wrote that “Obligations arise either from contract or from wrongdoing or by some special right from various types of causes” (D 44.7.1.pr). Gaius settled on the label ‘quasi contract’ to describe a large group of those other special rights. 
In 1888, writing in the same tradition in the second edition of the Harvard Law Review, J B Ames said without a trace of irony that “nothing impresses the student of the Common Law more than its extraordinary conservatism”. Ames described “quasi contract” as including “the fundamental principle of justice that no one ought unjustly to enrich himself at the expense of another”. This principle, like the notion that contractual obligations should be respected, conceals a vast morass of detailed rules which were yet to be explicated. 
130 years later, both the common law and the civil law are far advanced in the development of the detail of rules concerning liability for the unjust enrichment of a defendant at the expense of a claimant. A huge contribution has come from the work of English academic scholars. Some of those are in a direct line of academic teaching and learning from Goff and Jones to Birks and to Burrows. The line of teaching and learning has been heavily reductionist. Rules have been collected by reference to criteria such as “injustice”, “enrichment”, and “at the expense of the claimant”. Although the rules concerning unjust enrichment at the expense of another are now well developed there are still many difficult questions which remain. In Australia, question marks even surround the very existence of the subject. 
Against this background, Dr Ball’s book, Enrichment at the Claimant’s Expense: Attribution Rules in Unjust Enrichment, is notable in three respects. First, Dr Ball is Australian. He writes for an audience who are, in part, Australian and likely to be sceptical. To borrow a metaphor from one of the forefathers of the subject, he publishes in Australia from a Sherman tank. His book, the manuscript of which was submitted on the eve of Australia Day 2016, commences with a powerful and compelling methodological defence of his approach focusing upon the labels “top down” and “bottom up”. In Australia the former label is a term of extreme derision. But although Dr Ball’s thesis is powerfully anchored in case law, he notices, as did the progenitor of those labels (Judge Posner), that no coherent theory of law can ever be truly “bottom up” or “top down”.  
Secondly, Dr Ball writes as a scholar of the fifth generation in the direct line of English teaching and learning that commenced with Goff and Jones. Each step in that English learning has become increasingly more sophisticated without losing the clarity needed to communicate conceptual ideas. In England, I supervised the very early stages of the thesis upon which Dr Ball’s book is based. It was written at a time when the sophistication of legal scholarship in this area owed much in this area to the tango between the academy and the practising profession, and judiciary. Scenarios from cases, usually where billions of pounds are at stake, immediately expose the difficulty with generalised rules forged upon a limited mass of case law.  
Thirdly, Dr Ball has tackled directly the most difficult set of rules in the law of unjust enrichment. These are the rules concerning attribution. Perhaps the most sophisticated systemic attempt at these rules is the German approach. German law divides restitutionary claims into those based upon performance, leistungkondiktion, and those that are not based upon performance, eingriffskondiktion. Further and further subdivisions then occur. The complexity of the German approach contrasts with the simplicity seen in many of the English and Australian cases. But English and Australian law has been less successful. In the Court of Appeal in England it was claimed that the notion that an enrichment is at the claimant’s expense does “no more than point to the requirement that the immediate source of the unjust enrichment must be the plaintiff”. In Australia, it was said in the High Court that it was the “subtraction from the plaintiff’s wealth enables one to say that the defendant’s unjust enrichment has been at the expense of the plaintiff”. Neither of these approaches can be applied directly as a means of deciding cases. The first is simply wrong.  
Dr Ball’s thesis presents a deep intellectual challenge to anyone seeking to understand the law of unjust enrichment. Some strong academic voices will object to Dr Ball’s advocacy for a counterfactual test which, in areas such as the law of torts, has sometimes been abandoned in favour of tests such as whether an event was a contributing factor or exceptions where proof of causation is impossible. But those who object on this ground should bear in mind the subsequent English lament by Lord Sumption (judicially) and Lord Hoffmann (extrajudicially) that the abandonment of causation where proof is impossible is an exception that could not “be justified by reference to any general principle and depended on a distinction which had no rational factual or legal justification”. 
Dr Ball’s thesis is written for the future. It has one eye on normative concerns and the other on the descriptive analytical tradition of the common law. It is written to develop rules in an important and developing area of private law. It is conservative and highly technical. In short, it has all the hallmarks of outstanding scholarship.