The fourth edition of Conor Quigley's highly acclaimed book provides lawyers, regulators and public officials with a definitive statement of the law and practice of State Aid. The book places State Aid law and policy in its economic, commercial and industrial context, exploring the concept of State Aid and its function as a tool of EU law.All of this is achieved by a thorough examination of the jurisprudence of the European Courts and the decisions, legislation and guidelines of the Commission in declaring aid compatible or incompatible with the internal market.The fourth edition includes new chapters on: - COVID-19 and Ukraine emergency measures- Brexit- EU foreign subsidy regulation- UK Subsidies Control and updated guidelines and block exemption regulations on:- Regional aid- R&D&I - Environmental protection and climate change