U&A was defined by the Boldt Court proceedings; the Feds (I believe) even produced maps that clearly outlined each Tribe's U&A. That said, if a tribe develops data (primarily archaeological but perhaps also historical) they can take it to Federal Court. Tulalip did this in the 80s, as I recall.

The State's only action would be to cite fishermen who were fishing outside of the U&A defined by the courts. I don't think WDFW does this any more. The individual tribe would handle their response.

One possibility is that a tribe with U&A invites an outside tribe to fish. In which case, somebody else with U&A there might invite Lummi in.