Police and Judicial Co-operation in Criminal Matters
The Lisbon Treaty has a big chapter on Home and Justice Affairs including police cooperation. The title is called an Area of Freedom, Security and Justice. It is a shared competence - EU law therefore suppress member states' existing legislation and right to legislate in this area.
Was first introduced at the supra-national level under the Treaty of Amsterdam and is now an area in which qualified majority voting can be used, in accordance with the provisions.
Links
European Commisison: Freedom, security and justice http://ec.europa.eu/justice_home/doc_centre/police/doc_police_intro_en.htm