Legal theorists are familiar with John Finnis's book Natural Law and Natural Rights, but usually overlook his interventions in US constitutional debates and his membership of a group of conservative Catholic thinkers, the 'new natural lawyers', led by theologian Germain Grisez. In fact, Finnis has repeatedly advocated conservative positions concerning lesbian and gay rights, contraception and abortion, and his substantive moral theory (as he himself acknowledges) derives from Grisez. Bamforth and Richards provide a detailed explanation of the work of the new natural lawyers within and outside the Catholic Church - the first truly comprehensive explanation available to legal theorists - and criticize Grisez's and Finnis's arguments concerning sexuality and gender. New natural law is, they argue, a theology rather than a secular theory, and one which is unappealing in a modern constitutional democracy. This book will be of interest to legal and political theorists, ethicists, theologians and scholars of religious history.