The Constitution is just what it says it is, a compact delineating the basis upon which a union between the sovereign States, and any future States admitted, would be constituted and carried out. It’s function was not so much to empower the federal government to rule as it was to specify, limit, and rule the agency of the federal government in carrying out it’s delegated duties on behalf of the States in union. Patrick Henry, one of our most illustrious founding fathers, said it this way:
“The Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government – lest it come to dominate our lives and interests.“
You would think the explanation for this would be standard knowledge to the common American, especially considering most High School students are required to take a course in American civics and economics. Sadly however, not only do most Americans not understand the true function of the Constitution of these united States, evidently neither do most of our elected officials. That, or they just do not care.
Despite his total mockery of the same, and the novelty of his saying so upon the occasion and in the context which he did, Lincoln actually expressed (however hypocritically) the truth of this principle when he penned those infamous words “government of the people, by the people, for the people“, which the tenth amendment to the Constitution clarifies, “The powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people.” That is to say, among other things, that the states and “the people” are legally synonymous, via our democratic republican (or representative) system.
In short, the purpose and function of the constitution is to tell the federal government what it can and cannot do on behalf of the states. Thereby providing and affirming that “the people” are in charge of the government, not the other way around.