What defines American legal history in the twentieth century? This question may bring to mind blockbuster Supreme Court cases. At a time when familiarity with Supreme Court decisions is vanishingly rare, many know about Brown v. Board of Education’s desegregation of American schools and Roe v. Wade’s recognition of abortion rights. Others may point to the legal revolutions celebrated in many textbooks, from the New Deal to the Civil Rights Act of 1964. 1