American Samoa's Attorney General credits Governor Lolo Moliga for a favourable court ruling over what's called the Large Vessel Prohibited Area.
The US had made an amendment allowing longliners to fish within 12 miles from shore, whereas previously vessels could only fish 50 miles out.
The territory filed a suit saying the amendment had violated its sovereign rights.
Talauega Eleasalo Ale said he had been advised that it would be a difficult case to win, but the governor had told him to continue.
Talauega said without Lolo's persistence, he wouldn't have done the work to find supporting facts to prove the amendment was contrary to the provisions of the Deeds of Cession.
He said a major challenge was there was no case law on the Deeds of Cession so their research extended to deeds of other native people.
"We are native. We have aboriginal rights. So what we did is we looked outside of American law. We looked at the [New Zealand] Treaty of Waitangi, the secession of the Fiji people. We combined all of that. Again, I cannot say enough about my team [who] worked tirelessly to find those cases."