Fundamental identity of a people

There is a fifth, and in some ways the most fundamental, function a constitution performs: it expresses the very identity of a people. This isn't just a poetic way of putting it — a collection of individuals only becomes one political community, a single collective entity capable of acting together, by agreeing to a shared basic constitution in the first place. It is precisely by agreeing to a common set of norms about how the group is to be governed, and who is to be governed by them, that a group of people constitutes itself into one political community with a shared political identity. Before any constitution, individuals already carry many other identities — religious, regional, linguistic, and so on — but constituting themselves under one constitution creates something additional: a shared political identity layered over those pre-existing ones.

A constitution also gives a people a moral identity, because its authoritative norms define the values that community will not allow itself to trespass, becoming an overarching framework within which individuals then pursue their own personal goals and freedoms. And because many basic political and moral values (democratic government, protection of core rights) are now shared quite widely across very different constitutional traditions around the world, constitutions across countries resemble one another in these broad respects even while differing sharply in their procedural details. …