The subject of Justice and Home Affairs (JHA) within the European Union only developed during the early 1990s and has consequently been a relatively neglected area of study. This however is no longer the case as the EU has been expanding its activities in JHA matters to the point where they have become some of the most important areas of responsibility for the Union. The EU is engaged in the process of constructing an internal security regime that encapsulates police cooperation, mutual assistance in matters of civil and criminal law and the creation of a judicial network. This EU approach to internal security policy has come about in response to perceptions of threat. With the dismantling of Europe's internal borders and the rise of organized crime and illegal immigration, the EU has been working to develop policies to counter these challenges. The European Union and Internal Security investigates the development of these security challenges and the measures by which the EU seeks to combat them. With the imminent enlargement of the EU to central and eastern Europe, these security challenges are expected to grow.