It is a great honour and pleasure to be asked to deliver this year’s Sir David Williams lecture. The first time that I saw Sir David was on my first day of lectures as an 18 year old undergraduate, when he gave the first lecture I attended on constitutional law at the lecture theatre at Mill Lane. At that time, according to our timetable, he was known as Mr D. G. T. Williams. From that moment on his qualities became quickly apparent. He was not only a wise teacher but also a modest man. In my second year I had the privilege of being lectured by Sir David on administrative law. Towards the end of my undergraduate career here, I also had the benefit of advice from him as to the future. In particular he was one of those teachers who encouraged me to go to the USA. I followed in his footsteps in the sense that, like him, I was a Harkness Fellow and, like him, I studied at the University of California. I have therefore taken as my subject for this year’s lecture what I think would have been one of Sir David’s interests: that is a comparison between American and British perspectives on constitutional law. Inevitably these reflections will be selective, since the topic is so vast that it could easily take many years of study…..