Compulsory purchase powers are provided under a wide range of statutes for a wide range of purposes, but the vast majority are exercised through a common procedural framework. This chapter focuses on the major contemporary issues and challenges that have arisen in light of decisions relating to public interest, planning gain and private to private transfers. The fundamental basis of compulsory purchase is that the state has an underlying right to acquire land from the private landowner, but this is subject to strict requirements. State aid is generally considered to be an economic advantage derived through the selective use of State resources and which is therefore liable to distort competition. In considering the legal context of takings it becomes clear that the statutory requirement for a clear public purpose has become further enshrined by case law, and that the definition of this has been regularly tested, notably in terms of public takings to facilitate private schemes.