This new work clarifies Aquinas' concept of natural law through his biblical commentaries, and explores its applications to U.S. constitutional law. * The first time the use of Aquinas on the U.S. Supreme Court has been explored in depth, and its applications tested through a rigorous reading of the biblical commentaries * Shows how key judgments in the Supreme Court have rested on medieval natural law, and applies critical gender theory to discuss problems with these applications * Offers new research data to give a different picture of Aquinas and natural law, and a fresh take on Aquinas' biblical commentaries * New research based on passages in the biblical commentaries never before available in English