The application of public procurement regulation in the UK prior to its departure from the EU was based on the judicial activism of the CJEU which has been the most influential factor in developing and honing the concepts of the public procurement acquis and in providing for clarity and certainty to its decentralised application and enforcement. The UK legal procurement framework benefited from judicial activism and has been guided by a doctrinal interpretation which attempts to fuse the underlying principles of public procurement regulation with the fundamental principles enshrined in the EU Treaties. Such fusion has been achieved by supplementing the public procurement Directives with primary EU law. Public procurement has been viewed by both EU Institutions and Member States as an instrument for growth and competitiveness. The public procurement acquis has been subject to several reform agendae to introduce regulatory components for competitiveness and growth (See European Commission, Communication, Europe 2020, A strategy for smart, sustainable and inclusive growth, 3.3.2010, COM (2010) 2020 final.) in the delivery of public services in the EU. The Court of Justice of the European Union has inferred the themes for reform in the public procurement Directives. Judicial activism in public procurement reveals the EU primary law bias in its application and the quest for enhanced interoperability and regulatory homogeneity of the acquis through a simplified public procurement regime in the European Union, which will result in procedural efficiencies and streamlining the application of the substantive rules in the delivery of public services. The UK Public Procurement framework after its departure from the EU is set to reform the United Kingdom’s public procurement regime and to create a simpler and more transparent system not based on transposed EU Directives. The regulatory outcomes of the UK public procurement framework after Brexit are unknown because the system has not been yet applied and domestic or international judicial precedent is not generated. The imminent legal framework reveals its regulatory proximity with the principles, concepts and procedures applied by the previous regime. Nevertheless, deregulation of public procurement regulation in pursuit of simplification could increase transactional costs and bring about a deficit of legal certainty. Retained law on public procurement in the form of case law from the CJEU will act as a yardstick in formatting the applicability parameters of the new rules of the UK Public Procurement framework.