see my post #35. I don't have the paper she wrote about it on me. If I have it at home I'll post it, had some good sources.
I hate to burst your girlfriend's bubble, but twelve natuical miles is the generally accepted limit. There are some rules concerning situations where two points of land are less than separated by less than 24 miles of water and the nation in question can calim the waters in that bay as national waters.
The Hudson bay and the NW passage to not fit those rules any more than the Gulf of Sidra did with Libia. The U.S. routinely conducts freedom of navigation operations through international waters that some country is trying to claim as territorial waters, since to do otherwise could be seen over time as recognizing those claims as legitimate.