We can all agree that there are two different questions: (1) How courts actually have interpreted a provision of the Constitution (and thus how a good lower-court judge would apply it) and (2) How courts should have interpreted that provision based on whatever theory of constitutional interpretation a person adopts.
Those are indeed two different questions, but one thing that’s missing from Orin’s post is any sense that there are constitutional actors out there beyond the Supreme Court.
For example, let’s assume arguendo that current Supreme Court doctrine is clear that ObamaCare is constitutionally permissible. Does that mean that I, or anybody else, has to accept that as a “descriptive” matter, Obamacare is in fact constitutional? No, it doesn’t. I can still argue (a) that my Congressman should vote to repeal it because it is unconstitutional, regardless of what the Supreme Court says; (b) that if a Republican is elected president in 2012, he should refuse to enforce it and/or veto any implementing legislation, because it’s unconstitutional; and (c) that the Supreme Court should reverse itself, because it’s unconstitutional.
For that matter, interest groups and intellectuals on both the left and the right have at times been successful in implementing their agendas through constitutional arguments, even in the absence of any supportive Supreme Court precedent, and sometimes in the face of contrary Supreme Court precedent.
The best example is the National Rifle Association and other pro-gun organizations and the right to bear arms. Way before the Supreme Court recently recognized an individual right to bear arms, and indeed when existing precedent seemed to be to the contrary, constitutional arguments persuaded millions of Americans, and their legislators, that there is such a constitutional right. I think it’s pretty clear that if the Second Amendment didn’t exist, there would have been more gun control in the U.S. over the last several decades, even though from Orin’s perspective, “descriptively,” the Constitution did not protect the right to bear arms, especially not against the states, where late 19th century precedent was quite clear.
A somewhat more ambiguous but still telling example is the First Amendment’s guarantee of freedom of speech. The Supreme Court has strictly limited the First Amendment to contexts involving “state action.” Yet, thanks to the efforts of the ACLU and others, millions of Americans believe that the First Amendment protects a broader principle of freedom of speech that applies even to private parties. One often hears people making “First Amendment” arguments that the courts would laugh at, but these arguments have some real consequences. For example, various private organizations, such as private universities, voluntarily adopt more speech protective rules than they might otherwise, sometimes explicitly adopting First Amendment doctrine as their guideposts, even though, “descriptively,” the First Amendment is wholly inapplicable.
One could go on with other examples, including the Free Exercise Clause, the Tenth Amendment (a clear takeover by the Federal government of certain traditional state and local functions would raise constitutional hackles, regardless of what the Supreme Court says), and so on.
All of which is to say that “constitutional law”, even descriptively, is not limited to what the Supreme Court says it is.