The role of the Court of Justice is to ensure that EU law is interpreted and applied in the same way in every EU country so that countries and EU institutions abide by EU law.
It is used to settle legal disputes between national governments and EU institutions and can also be used by individuals, companies and organisations to take action against an EU institution if they feel it has infringed their rights.
The court is divided into 3 bodies:
Court of Justice – deals with requests for preliminary rulings from national courts, certain actions for annulment and appeals. It consists of 1 judge from each EU country plus 11 Advocates General.
General Court – rules on actions for annulment brought by individuals, companies and, in some cases, EU governments. In practice, this means that this court deals mainly with competition law, State aid, trade, agriculture, trade marks. It consists of 1 judge from each EU country.
Civil Service Tribunal – rules on disputes between the EU and its staff. It consists of 7 judges.
Court of Justice of the European Union (http://europa.eu/about-eu/institutions-bodies/court-justice/index_en.htm)
Court of Justice website