What does the Constitution do?

Why this is the answer

The Constitution is the document that creates the federal government and then fences it in. It builds three branches, legislative, executive and judicial, and spells out what each one may do, which is why "sets up the government" and "defines the government" are both accepted. It also divides power between the national government and the state governments, an arrangement called federalism. And through the first ten amendments it establishes rights and liberties that belong to every American, which is the third accepted answer. Any one of the three passes. Memory hook: the Constitution builds the government, describes it, and limits it.