Mike Ramsey has another post about the Dormant Commerce Clause (DCC), following up on my previous post and this post by Mike Greve. Mike Ramsey attempts to set forth the strongest arguments against the DCC, with which I agree. There is no good original meaning argument for the DCC.
There is, however, a somewhat stronger argument for an exclusive Commerce Power. Unlike the DCC, one could conceivably conclude that the Commerce Clause provides exclusive authority to the federal government to regulate interstate commerce. That would differ from the DCC because the exclusive authority would take away from the states all authority to regulate interstate commerce, not just the power to discriminate against interstate commerce.
While Chief Justice Marshall toyed with this argument, and there us something textually to be said for it, I still don’t think it works for three reasons. First, the Commerce Clause does not say that it is exclusive and one would not normally infer from the language that the power was exclusive. Second, as Mike Ramsey notes, the Constitution seems to provide for exclusive power by doing so expressly, as when it states that Congress shall have the power “to exercise exclusive legislation in all cases whatsoever” over the District of Columbia. Third, the Constitution seems to recognize that the states can pass laws involving interstate and foreign commerce, as it provides that “no state shall, without the Consent of the Congress, lay any Imposes or Duties on Imports or Exports, except what may be absolutely necessary for executing its inspection laws” (although there is a complicated counterargument involving this provision).