You were analyzing Art. I, Sec. 8 where it says: "To regulate commerce with foreign nations, and among the several states, and with the Indian tribes;..."
You said:
The key word here is "regulate". I asked if you would give the Feds "full control over with whom or where its citizens may trade." If your answer is "yes", depending on this clause, then you feel "regulate" can include complete prohibition.
As between our nation and foreign nations, yes, clearly it can. You don't think so? Prove it. Detail your logic. Cite your scholars, call up Alan Dershowitz. Whatever.
Therefore, the Feds, under your interpretation, could ban interstate commerce between California and Arizona, with or without reasons. Is that your position as well?
No. You fail to recognize the key distinctions between internal and external. Yours is therefore an insupportable reading of the Constitution. You fail to read it together. I.e., you miss this modifying portion which precedes it:
and provide for the common defense and general welfare of the United States; but all duties, imposts and excises shall be uniform throughout the United States.
Anything done to effectuate your hypothetical ban, or even something less, has to be uniform. No ban could be made against one U.S. state, without it being applied to all. Has to be uniform. So the nature of the regulation internally is constrained, so that we have a fair and free internal market. But externally, no, there is no similar requirement. At all.
And quite intentionally so. The Federal control of which was deliberately magnified to strengthen the UNION. United we stand, divided we fall.
IMHO, Federal regulation of commerce with foreign nations must include the power to prohibit, in order to be able to effectively answer prohibitions placed on our own goods by other nations. Among the several state no such power is necessary. They have to authority to lift any prohibition imposed by an offending state.