In the US, one out of every 138 residents is incarcerated. The size of the prison population has quadrupled since 1980. Approximately 2.4% of Americans are either on probation and parole. The US has the highest rate of criminal punishment in the Western world. The problem with American criminal law, as the philosopher of law Douglas Husak and many others see it, is that there is simply too much of it. Recent years have seen a dramatic expansion in the amount of criminal statutes, and in the resulting reliance on punishment for convictions under those laws. Husak argues that this is regrettable for several reasons, but most importantly, he says that much of the resulting punishment is unjust, excessive, and disproportionate. He also claims that it is destructive to the rule of law and undermines the principle of legality. What should be done? Husak's goal in this book is to formulate a normative theory of criminalization that will allow us to distinguish which criminal laws are justified, and which are not--something he sees as essential in order to reverse the trend towards too many criminal laws. The first part of his book makes the case that there is both too much criminal law and too much punishment, and clarifies the relationship between the two using empirical data. He then provides examples of dubious criminal laws enacted by legislatures, in particular statutes on drugs possession and guns. The latter part of the book develops his theory, which establishes principles that should set limits (both external and internal to the criminal law) on what we can and should criminalize.