Background on legal process (source document)
Article 258 of the Treaty on the Functioning of the European Union (TFUE) gives the Commission the power to take legal action against a Member State that is not respecting its obligations under EU law.
The infringement procedure begins with a request for information (a "Letter of Formal Notice") to the Member State concerned, which must be answered within a specified period, usually two months.
If the Commission is not satisfied with the information and concludes that the Member State in question is failing to fulfil its obligations under EU law, the Commission may then send a formal request to comply with EU law (a "Reasoned Opinion"), calling on the Member State to inform the Commission of the measures taken to comply within a specified period, usually two months.
If a Member State fails to ensure compliance with EU law, the Commission may then decide to refer the Member State to the Court of Justice. However, in over 90% of infringement cases, Member States comply with their obligations under EU law before they are referred to the Court. If the Court rules against a Member State, the Member State must then take the necessary measures to comply with the judgment.
If, despite the ruling, a Member State still fails to act, the Commission may open a further infringement case under Article 260 of the TFEU, with only one written warning before referring the Member State back to Court. If the Commission does refer a Member State back to Court, it can propose that the Court imposes financial penalties on the Member State concerned based on the duration and severity of the infringement and the size of the Member State (both a lump sum depending on the time elapsed since the original Court ruling and a daily penalty payment for each day after a second Court ruling until the infringement ends).