There is a procedure for establishing whether a Member State has failed to fulfil an obligation imposed on it by Community law. Given the seriousness of the accusation, the referral of the Court of Justice must be preceded by a preliminary procedure in which the Member State is given the opportunity to present its observations. If the dispute is not settled at that stage, either the Commission or another Member State may commence an action in the Court. In practice the initiative is usually taken by the Commission. The Court investigates the complaint and decides whether the Treary is infringed. If so, the offending Member State is then required to take the measures needed to conform. If a Member State fails to comply with a judgment given against it, the Treaty on European Union offers a new possibility of ordering it to pay a lump-sum fine or a penalty payment (Article 171 of the EC Treaty, as amended by the Treaty on European Union).
Klaus-Dieter Borchardt, The ABC of Community Law, European Commission, 1993, p.51