The new edition of the commentary is based on the latest HOAI amendment from 2013. The core of the amendment is the technical revision of the service descriptions and the update of the fee rates in the fee tables. The commentary provides construction lawyers, architects, and engineers with quick and comprehensive access to the latest legal status. In clear language, yet scientifically grounded and, above all, solution-oriented, the authors engage with the amended HOAI. The new edition also includes an extensive introduction to architectural and engineering law and presents the current status of architectural contract law and architect liability. The authors have incorporated both the specialized literature published since the amendment and the subsequent case law.