Complex sentence: In 1987, the U.S. Supreme Court ruled in "California v Cabazon Band of Mission Indians" that as sovereign political entities, tribes could operate facilities free of state regulation.
Split into simpler sentences: In 1987, the U.S. Supreme Court delivered the decision in "California v Cabazon Band of Mission Indians". In this case, the Court ruled that as sovereign political entities, tribes could operate facilities free of state regulation.