I suppose we are supposed to believe it is the "ability" to contractually consent away the jurisdiction of constitutional courts in lieu of an international dispute board, even though neither the treaty, the dispute courts, nor were the officers of said courts approved by the 2/3 of the Senate.
is there a North American Union ping list?
Rather than copying the Europeans (there is very little to gain from Europe currently), Mexico and Canada should be encouraged to become part of the United States; for Mexico there could be status of territory longer, until it reaches a status close to the United States (Alabama is the lowest, so that state could be used as a threshold).