On March 26, 2012, the Transportation Research Board published Legal Research Digest 13: An Index and Digest of Decisions: Compilation of Airport Law Resources. The Digest contains summaries and links to more than 400 federal court cases on the subject of airport law. The cases are organized by keywords, airports, and courts to help users find relevant court opinions without having to rely on fee- or subscription-based services. Kaplan Kirsch & Rockwell prepared the Digest under contract to TRB.