In 2024, the Federal Railroad Administration issued its Crew Size Rule, which by default requires freight trains to operate with at least two crewmembers but allows one-person crews through a notice process for many smaller railroads and through special approval when a railroad shows a one-person operation is as safe or safer. Six railroads and two industry groups, including the Association of American Railroads and the short line railroad association, petitioned for review, and the cases were consolidated in the Eleventh Circuit. The Eleventh Circuit held that the rule was within the agency’s authority and was not arbitrary or capricious, and it denied the petitions. The court read the statute’s authorization to issue safety regulations “as necessary” as a grant of discretion about when to regulate rather than a stringent evidentiary bar, and it concluded that the agency reasonably explained its shift from a 2019 decision not to regulate, adequately responded to comments seeking more data, did not have to count lost savings from one-person crews as a cost, and was not required to vacate the rule for missing a 12-month rulemaking deadline. It also rejected the short line railroads’ objections to the legacy exception, several of which were forfeited, and to the expanded alerter requirement for one-person crews, finding that the agency acknowledged the change and gave good reasons for it. Judge Branch dissented, arguing that the agency relied on substantially the same data it found insufficient in 2019 and ignored the labor costs of keeping two-person crews, so the rule should have been vacated as arbitrary and capricious.