46 U.S.C. § 40701: Rates

maintain a rate or charge in a tariff or service contract, or charge or assess a rate, that is below a just and reasonable level; or establish, maintain, or enforce in a tariff or service contract a classification, rule, or regulation that results, or is likely to result, in the carriage or handling of cargo at a rate or charge that is below a just and reasonable level. The Federal Maritime Commission, at any time after notice and opportunity for a hearing, may prohibit the publication or use of a rate, charge, classification, rule, or regulation that a controlled carrier has failed to demonstrate is just and reasonable. In a proceeding under this section, the burden of proof is on the controlled carrier to demonstrate that its rate, charge, classification, rule, or regulation is just and reasonable. A rate, charge, classification, rule, or regulation that has been suspended or prohibited by the Commission is void and its use is unlawful.