Brexit, the possible break-up of the UK, pandemics, this is a country in crisis. In crises the law sets the boundaries of what the government can and should do. But in a country without a written constitution such as the UK, the precise limits between legal obligation and convention can be hazy. Conventions, such as the Prime Minister being an MP, cannot be enforced in the same way as laws. What are the limits of law in politics? What is the relationship between law and the constitution? Is not having a constitution a hindrance or a help in time of crisis? Former supreme court judge Jonathan Sumption wrestles with past, current and potential crises that this increasingly divided country faces. From the role of the Supreme Court to the uses of referenda to the rise of nationalisms within the UK, Sumption exposes the subtleties, uses, and abuses of legal and judicial interventions.