Noah Millman pushes back on Conor's worries:
As for whether the Constitution has any meaning if there are no restrictions on Federal power: well, the reason we have a Bill of Rights is precisely that the anti-Federalists worried that there was no restriction on Federal power built into the original Constitution. But that doesn’t make the Constitution meaningless, because the Constitution also outlines the separation of powers what the respective roles of the President, the Congress and the Judiciary are, and how they interact. It is not meaningless that Congress has the power to tax and to regulate interstate commerce; that means the President cannot simply issue edicts.
It is not meaningless that Congress has the power to declare war though we’ve striven mightily to make that provision meaningless. It is not meaningless that it requires Constitutional amendment to change the composition of the Senate from two-senators-per-state to something more proportional, or that it required a Constitutional amendment for Senators to be elected directly by the people rather than appointed by state legislatures. It is not meaningless that the Constitution specifies life tenure for the federal judiciary. I could go on. The implicit assumption that the Constitution’s only possible role is to limit the scope of government is not only wrong, it’s silly because Constitutions are only pieces of paper. What actually limits government is the existence of opposing forces, and a major function of the separation of powers is to establish such opposing forces within the government itself. The health-care mandate, for example, if it is struck down will be struck down by the courts courts which are a creation of the Constitution.