Complex sentence: It is a maritime law that refers to federal statute 46 USC section 883, the act that controls coastwise trade within the United States and determines which ships may lawfully engage in that trade and the rules under which they must operate.
Split into simpler sentences: It is a maritime law refers to federal statute 46 USC section 883. This is the act that controls coastwise trade within the United States and determines which ships may lawfully engage in that trade and the rules under which they must operate.