You're completely ignoring the substance of my question. Of course I understand that the US constitution doesn't allow racial discrimination. Surely its the case that racial discrimination is inherently bad and THEREFORE the US constitution prohibits it. Do you really want to hold the position that racial discrimination is bad BECAUSE the US constitution prohibits it?

You seem to ascribe very special moral rights to this particular association of people that we call democratic states. Why is the USG allowed to ban foreigners from coming to the US if they undercut American wages? Is New York State allowed to ban people from NJ from working in NYC by a majority vote (or a super-majority vote)? Again, I'm not asking whether the US constitution allows this - I know that it doesn't. The question is regarding ethics not law.