This book investigates the evolution of the legal concept of state aid within the European Union, questioning how the definition has shifted from its origins in the internal market to its current role in competition law. Juan Jorge Piernas López, a scholar in European law, utilizes historical case law and economic analysis to trace the development of state aid regulations. He argues that the legal boundaries of state aid are not static but have been continuously redefined by the Court of Justice of the EU to reflect changing political and economic priorities since the 1950s.

Legal scholars and practitioners identify this work as a rigorous examination of the doctrinal shifts in EU state aid law. Readers frequently note the academic density of the prose, making it a specialized resource for those studying the intersection of EU competition policy and internal market integration.