Articles 81 and 82 of the Treaty establishing the European Community prohibit all anticompetitive practices which may affect trade between Member States, as well as abuse of dominant position. The European Commission is the body commissioned with safeguarding the maintenance of effective competition in markets of a community scale or that affect several European Union Member States.
Until 2003 the European Commission had a monopoly on administrative implementation of European Community competition law. The trend in recent years, however, has been for a greater role to be taken on by national competition authorities (the CNC in the case of Spain), which can investigate community cases in certain circumstances, with the European Commission maintaining in all events its role as coordinator (in the European Network of Competition Authorities (ECN) and retaining decision-making powers for the most important cases.