The Federal Maritime Commission has issued new guidance about how it will assess the reasonableness of detention and demurrage regulations and practices of ocean carriers and marine terminal operators (MTOs) under 46 U.S.C. 41102(c). The final rule, “Docket No. 19-05, Interpretive Rule on Demurrage and Detention under the Shipping Act”, will become effective upon its publication in the Federal Register. Under the new rule, the Commission will consider the extent to which detention and demurrage charges and policies serve their primary purpose of incentivizing the movement of cargo and promoting freight fluidity. The rule also provides guidance on how the Commission may apply that principle in the context of cargo availability (and notice thereof) and empty container return.