Some of the Supreme Court’s most important decisions have, by design, been unanimous. In landmark cases, the court has at times recognized that the force of the ruling’s bottom line is more important than the specific legal principles at stake — that there are some cases in which it’s more essential for the court to speak with one voice than to air every possible legal argument.
The court insisted on unanimous opinions, for instance, in critical civil rights cases, such as Brown v. Board of Education, “Brown II,” and Cooper v. Aaron, decisions that found school segregation to be unconstitutional and ordered school districts to desegregate. It had done the same in Ex parte Quirin, a 1942 case that had upheld the government’s use of a military tribunal to try eight German saboteurs caught in the United States during World War II. We know from the justices’ private papers in each of these cases that it wasn’t that the justices each agreed with every word of the court’s opinions; they simply agreed that the cases were important enough that they shouldn’t be determined by a divided vote, and that the reasoning shouldn’t be called into question through separate opinions.