When Supreme Court Justices want to justify overruling long-standing precedent, the paradigm often cited is Brown v. Board of Education, from 1954, which, in declaring segregation unconstitutional, overruled Plessy v. Ferguson and its “separate but equal” doctrine, from a half century earlier. During the last term, Justice Samuel Alito offended many people when he compared the Court’s overruling of Roe v. Wade to Brown’s overruling of Plessy. (He continued to offend people last week, when a new book by John A. Farrell revealed that, during Alito’s confirmation hearings, he had privately told Senator Ted Kennedy, in reference to Roe, “I am a believer in precedents.”)