This case was concerned with the nationalisation of the Italian electricity industry, whose bills Costa refused to pay in protest (he had a stake in the private energy firm) since he said its creation breached EU law. The Italian Constitutional court said that subscription to the EC was an ordinary law, subject, like any other, to repeal. The ECJ ruling overturned this, saying (1) that upon the EEC Treaty coming into force a “new legal order” came to exist, which caused EC law to enter into domestic law and that domestic courts are “bound to enforce” it. And (2) that “transfer from [member states’] domestic legal systems to a Community legal system” meant a loss of sovereignty and hence any subsequent act made in breach of EC law would be ineffective, since EC law would prevail. This ruling established that member states couldn’t deviate from EC treaties without prior permission. It also established that national high courts couldn’t determine incompatibility of national and EC law without consulting ECJ.