The central purpose of this book is to identify and explain the moral foundations of constitutional rights, the moral reasons that justify recognizing and applying them in the legal system of a nation state. A necessary preliminary is to understand what constitutional rights are. Hence, the fi rst two chapters deal with constitutional law and constitutional rights respectively. I argue that any adequate theory of constitutional rights needs to explain four species of rights: rights of governing institutions, public offi cials, private persons and associations. Judges sometimes appeal to moral reasons when they interpret the content of an established constitutional right or decide whether some claimed constitutional right really exists. Hence, there are many references to Supreme Court cases in Chaps. 3 , 4 , 5 and 6 . These illustrate judicial reasoning about how moral reasons succeed or fail to ground an actual constitutional right. The focus of Chaps. 3 , 4 , 5 and 6 is ongoing political debates about controversial constitutional rights, some established in United States law and others merely proposed. It is here that the moral reasons for or against any constitutional right are most easily identifi ed and their relevance most clear. Many of these debates are described in some detail and examined with care in these chapters. My examinations are critical, that is, they go beyond merely describing these debates to an assessment of the relative importance of the pro and con reasons advanced and to reach conclusions about whether each of these constitutional rights ought or ought not to be retained in our legal system or introduced into it. I do not imagine that I can settle any of these debates. My intentions are to assist others to continue the ongoing discussion of controversial rights more reasonably and to reach some theoretical conclusions about when and how moral reasons succeed or fail to justify any constitutional right. Although the focus of this book is on constitutional rights in the United States, my theoretical theses and assessments of the relevant moral reasons will be applicable to the constitutional law of many other nation states.