Complex sentence: In that case, James Smith sought to have a case heard in federal court which he had previously brought in a tribal court; when he disagreed with that court's decision, he claimed that the tribal court had had no jurisdiction in the first place.
Split into simpler sentences: In that case, James Smith sought to have a case heard in federal court which he had previously brought in a tribal court. When he disagreed with the tribal court's decision, he claimed that it had had no jurisdiction in the first place.