The Court of Justice of the European Union (CJEU) is a body of the European Union responsible for ensuring that EU law is interpreted and applied in the same way in every EU country, and that EU countries and EU institutions abide by EU law. The Court gives rulings on cases brought before it.
The most common types of case are:
interpreting the law (preliminary rulings) – national courts of EU countries are required to ensure EU law is properly applied, but courts in different countries might interpret it differently. If a national court is in doubt about the interpretation or validity of an EU law, it can ask the Court for clarification. The same mechanism can be used to determine whether a national law or practice is compatible with EU law.
enforcing the law (infringement proceedings) – this type of case is taken against a national government for failing to comply with EU law. Can be started by the European Commission or another EU country. If the country is found to be at fault, it must put things right at once, or risk a second case being brought, which may result in a fine.
annulling EU legal acts (actions for annulment) – if an EU act is believed to violate EU treaties or fundamental rights, the Court can be asked to annul it – by an EU government, the Council of the EU, the European Commission or (in some cases) the European Parliament.
Private individuals can also ask the Court to annul an EU act that directly concerns them.
ensuring the EU takes action (actions for failure to act) – the Parliament, Council and Commission must make certain decisions under certain circumstances. If they don't, EU governments, other EU institutions or (under certain conditions) individuals or companies can complain to the Court.
sanctioning EU institutions (actions for damages) – any person or company who has had their interests harmed as a result of the action or inaction of the EU or its staff can take action against them through the Court.
Over the years, the Court has dealt with several cases related to Internet matters, such as: retention of data by providers of electronic communication services, the right to be forgotten, privacy and data protection, and liability of online intermediaries.