The US Congress passed the Longshore and Harbor Workers’ Compensation Act (LHWCA) in 1927; it is administered by the US Department of Labor, Division of Longshore and Harbor Workers’ Compensation (DLHWC), and provides medical benefits, compensation for lost wages, and rehabilitation services to longshoremen, harbor workers, and other maritime workers such as pier, wharf, dock, or terminal workers who are injured during employment or suffer diseases caused or worsened by employment conditions. The LHWCA and the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) similarly define many terms (eg, injury, disability, impairment, permanent). Under the LHWCA, impairment ratings are performed for “scheduled injuries,” and disability benefits are determined by multiplying the percentage of “permanent disability” (eg, “permanent impairment”) for a specific body part by a specified number of weeks. For DLHWC impartial medical specialty evaluations, specific steps are taken to avoid prejudgment of a case, and contested cases are heard before administrative law judges. Physicians who perform impairment ratings should understand not only how to fairly rate permanent impairment according to the AMA Guides but also the specific needs of the groups that request these evaluations. Impairment ratings are required for scheduled injuries, hearing loss, and occupational disease cases covered by the LHWCA; physicians must express extremity ratings as the most distal body part applicable, not as a whole person impairment.