In the context of the far-reaching reforms proposed for the Appellate Committee House of Lords and the Judicial Committee of the Privy Council, Building the UK's New Supreme Court considers the operation and reform of courts at the apex of the UK's legal systems. The chapters are linked bybroad and overlapping themes. The first of these is the complexity of accommodating national differences within the UK into the institutional design of the new supreme court. It will be not only a court for the UK's three legal systems, and simultaneously a national institution of the whole UK, butit is also likely to be called upon to resolve division of powers disputes within the emerging system of multi-level government. A second theme is the scope for comparative lesson-learning from top courts in other legal systems: the Supreme Court of Canada, the US federal courts system, and theconstitutional courts in Germany and Spain are considered. Thirdly, the connections between the UK's top-level court and other courts, especially intermediate courts of appeal, the European Court of Justice, and the European Court of Human Rights are examined.