"Arguing that they didn't have any legal ground to stand on," is a tough thing to say, considering I can't imagine there's much legal ground going the other way either. This sounds very isolationist, although, it's strange to have isolationist policy on a state-by-state basis, in the United States. I had always thought that the USA was a unified nation of multiple states, more for the purpose of dividing power up to grant additional freedom, and prevent oppression, rather than as a reason to prevent trade and contact.