U.S. airports that receive assistance from the federal government are required to comply with a number of obligations imposed by federal law. The TRB Airport Cooperative Research Program’s ACRP Legal Research Digest 21: Compilation of DOT and FAA Airport Legal Determinations and Opinion Letters as of December 31, 2022 covers legal matters that include the reasonableness of contractual terms, leasing practices, airport rules and regulations, airport charges imposed on aeronautical users, including a…