Legal transplant chronicles: The evolution of unreasonableness and proportionality review of the administration in the United Kingdom

The study of legal transplants seems to have reached its saturation point. Its richness has both contributed to conceptual confusion and obscured persistent assumptions about the nature of the migration of laws that are no longer valid in today's "flat" world. This Article aims to map the different definitions of and approaches to this concept by offering a graphic presentation of a series of typologies and distinctions that serve to encapsulate the various aspects of the debate. It then focuses on aspects that have received insufficient attention, and advances a renewed model of the transplant process that draws on today's complex reality rather than on the classical assumptions that served as a basis for early debate. Simple accounts of transplants as single events, through which an importer system adopts the laws of an exporter system, should be replaced by long-term accounts of series of interacting transplant events generated by a multitude of players. The model is applied in a case study that chronicles the evolution of the two British grounds of substantive review of the administration, unreasonableness and proportionality. Both have evolved through complex processes that involve innovation, vacillating degrees of loyalty to European doctrine and reliance on Commonwealth sources of influence. The application of the model not only provides a real-life example of the evolution of law in practice, it also offers readers a glimpse of the development of British public law and the impact of foreign law. Here, I proffer a novel emphasis on the impact of Commonwealth law. The literature in this context usually focuses on one actor. European law is considered, at least impliedly, as the central source of influence. Yet British courts first obliquely rejected European pressure by reverting to tests seemingly developed in Commonwealth countries (which, in fact, largely resemble German jurisprudence, once again without disclosing this influence). Ending with an assessment of the current state of affairs and possible future reliance on other sources of influence (the United States included), I show that no transplant is an island, and that complex modes of interaction color the process.