Abstract
The Brexit process challenges the principle of parliamentary sovereignty, the Grundnorm of the British constitutional system, in a number of ways. This chapter analyses three of them: the challenge brought by the use of referendum to decide on the UK membership of the EU; the effects on executive–legislative relations; and the problems raised by the existence of devolved legislatures in Scotland, Wales and Northern Ireland. These key challenges are addressed by looking in particular at the judgments of the courts, especially of the Supreme Court, which now, more than ever, seem to be of decisive importance in guiding the evolution of the UK form of State and government. The analysis shows how the principle of parliamentary sovereignty tends to resist these challenges and how such tensions seem to pave the way for its further development.