A constitution is a technology for binding power — a set of rules that today’s government must follow because yesterday’s decisions made them binding. The central puzzle is how this can work at all: if the sovereign is supreme, who enforces the limits on the sovereign?
The United States Constitution was written in 1787 by people who are all dead. It limits what Congress can do today. It determines what rights Americans have now. How can the decisions of people two centuries ago bind the living? That is the question constitutionalism has never fully resolved — and the struggle to answer it is the history of constitutional government.