Day to day enforcement of Community legislation is the responsibility of Member States. Any event suspected to be a breach of Community legislation should be communicated at first to the competent authority of the Member State concerned.
If it appears that a competent authority of a Member State fails to apply Community rules, the Commission may consider opening an infringement procedure under Article 226 of the Treaty against the Member State concerned. The Commission may initiate an infringement procedure based on consistent, sufficient and reliable data. Information concerning the failure of a Member State to apply Community rules can originate from the services of the Commission as an official mission report from the Food and Veterinary Office or from complaints by organisations or individuals.
Article 226 Treaty establishing the European Community (Amsterdam consolidated version - in force since 1st May 1999)
If the Commission considers that a Member State has failed to fulfil an obligation under this Treaty, it shall deliver a reasoned opinion on the matter after giving the State concerned the opportunity to submit its observations. If the State concerned does not comply with the opinion within the period laid down by the Commission, the latter may bring the matter before the Court of Justice.