Criminal law, according to George Fletcher, has become localized law in the sense that each country and, within the USA, each state has adopted its own set of criminal codes, conceptions of punishable behaviour, etc. In this book, Fletcher maintains that there is much greater unity among diverse systems of criminal justice than commonly realized, and that any adequate system of criminal law necessarily must address a set of universal, basic issues. He introduced and sets out the twelve concepts that shape and guide every system of criminal justice, knowledge of which is essential to understanding the structure of the law and its local and national variations.