The European Court of Justice (ECJ) has ruled on whether social insurance associations administering statutory work accidents and occupational disease schemes are "undertakings" for the purposes of EU competition law. The issue came before the ECJ in the Kattner Stahlbau case (C-350/07), on a reference from a court in Saxony (Germany). In 2004, a steel construction company, Kattner Stahlbau, challenged the obligation to take out compulsory occupational accident insurance with the local social insurance association, MMB, after deciding to take out private insurance. Kattner Stahlbau appealed the decision on the basis that MMB's monopoly was an abuse of a dominant position under competition law and a breach of the EC Treaty provisions on free movement of services. One issue put to the ECJ by the national court was, whether a body such as MMB, could be regarded as an "undertaking" under competition law. The ECJ ruled that, where a mandatory insurance association is fulfilling an exclusively social function, operating on the principle of solidarity and under state supervision, it is not an "undertaking" for the purposes of competition law. Moreover, although a mandatory occupational insurance scheme is likely to restrict or deter free movement of services, this may be justified, if it meets a public interest objective such as ensuring the financial balance of the social security system, provided that it is no more restrictive than necessary.