Not many choices, so "if they succeed" all that means is that the federal courts are open to handle federal suits.
HISTORY NOTE: The Pine Ridge Reservation extends all over the place. There are a couple of ancient sacred sites that show up as little outliers South in Nebraska further East. Those are graveyards. Just about anybody ~ white, black, Indian, whatever ~ who dies in the area ends up there. Folks doing geneology may be surprised to find a non-Indian ancestor on the list of burials.
Pine Ridge Rez is in SoDak.