He could hold the deciding vote in a pair of cases involving the use of race to determine which public school a child will attend.
And during today's oral arguments, Supreme Court Justice Anthony Kennedy joined his conservative colleagues in voicing skepticism about the programs in Seattle and in Louisville, Kentucky. The court is considering whether the programs in those cities are acceptable moves toward student diversity -- or if they are instead illegal racial quotas.
Kennedy said of the system-wide assignment plan in Louisville that "it's a troubling case."
But the court's four liberal justices indicated that they see no constitutional problem with school districts that consider a student's race in order to have individual school populations resemble the racial makeup of the whole system.
Federal appeals courts have upheld both programs.
An attorney for the Louisville schools called the plan a success story -- and says it has the support of parents of white and black students.