The opinions are here. Justice Scalia wrote for the Court; Justice Stevens, along with Justice Souter, concurred and offered a one-paragraph addendum which concludes: “I recall my esteemed former colleague, Thurgood Marshall, remarking on numerous occasions: ‘The Constitution does not prohibit legislatures from enacting stupid laws.'” Justice Kennedy, joined by Justice Breyer, concurred in the judgment.
The result in this case is not surprising, nor is the unanimity. I think the part that will get the most attention from election law scholars is the discussion in Justice Scalia’s opinion rejecting an idea that “one party entrenchment” violates the First Amendment and Justice Kennedy’s concurrence, which reads the First Amendment as providing more protection for the electoral process. No doubt, too, we will be examining Justice Kennedy’s opinion for what it might tell us about how the Court will rule in Crawford, the Indiana voter ID case.