That has nothing to do with U.S. law. It's pitful to suggest that it does.
Walt
I'm not suggesting that it is US law - you finally understand! Justice Grier wrote the opinion of the majority, and by his own words opined that the legal justification of the blockade was via International (between nations) law. Despite your oft repeated assertions that they cited the Militia Act as justification, if the Acts contained the necessary powers there would be no need to justify the blockade by the "Law of Nations", simply cite the revelant US law and be done with it.
And last time I looked, the Supremacy clause does not include international law, nor does it require US laws to operate in foreign countries.