The EU and its Member States have a wide range of laws to protect human health and the environment. The Commission is tasked with ensuring that Member States comply with these laws. Preventive measures are more effective and considerably cheaper than having to undo the damage caused by unsustainable practices. That’s why the Commission promotes a proactive approach that begins with informal discussions and support to apply the EU rules («compliance promotion»). If this fails to produce results, and the matter is not properly addressed at national level, EU legal action follows. The formal procedure begins with a letter of formal notice and may end in front of the Court of Justice of the EU. If a Member State fails to abide by a Court ruling, a second referral to Court and fines may ensue. This factsheet looks at a recent study of a selection of 244 infringement cases (out of several thousand cases in total) that were handled between 1994-2014 in several areas of environmental policy – waste management, water, industrial emissions, nature protection and environmental impact assessments. The results show that EU enforcement action brings considerable benefits for citizens and environment. These can take different forms. In some cases, EU legal action reduced the economic costs and losses that typically result from damage to human health and the environment when environmental legislation is flouted. In other cases, it contributed to a better quality of national legislation and decision making.