Introduction The focus of this volume is the migration of constitutional ideas across international borders and national jurisdictions. Many of the chapters presented here also focus on the positive influences of such migration, be it through charting the course for aspirational constitutionalism or supplying negative benchmarks for aversive cross-constitutional influence. This chapter looks instead to influences that, while taking place across borders, occur within a single ‘control system’ such as Great Britain and Northern Ireland or France and Algeria. The chapter uses the context of emergency regimes to sound a word of caution about certain aspects of legal or constitutional copying. Specifically, the chapter looks at concrete examples of the collapse of mechanisms that were designed to maintain different yet connected marketplaces of constitutional ideas segmented from each other. In theory, one part of a control system – the controlling territory – applies an emergency regime to the dependent territory. At the same time, a putative normal legal regime is maintained in the controlling territory itself. The two legal regimes apply contemporaneously. The dependent territory becomes an anomalous zone in which certain legal rules, otherwise regarded as embodying fundamental policies and values of the larger legal system, are locally suspended. However, the claim is that the two realities and the two concomitant legal regimes – that of emergency applicable to the dependent territory and that of normalcy applicable to the controlling territory – are maintained separately and do not affect each other.