Highest national courts were conceived at the pinnacle of the national court hierarchy, with one of their main tasks being the maintenance of a degree of legal coherency within the national legal system. Very often such courts also have the ability to declare national laws in violation of the constitution or international treaties. The interactions within societies and legal systems have consequences on highest national courts, which also increasingly interact with each other. This book investigates the theoretical and practical implications of these phenomena, offering a unique and unprecedented perspective on the issue of highest courts and globalisation from the world's leading scholars and judges.