Justice Kennedy, who reveres the popular initiative, voted with the Court’s four liberals to uphold the commission; Chief Justice Roberts dissented bitterly, protesting not only that the commission system violates the Constitution, but that this particular commission didn’t seem so all-fired independent to him.

Soon after its decision in the first case, the Court “noted probable jurisdiction” (meaning it found a serious issue to be settled) in Harris v. Arizona Independent Redistricting Commission, which looks at the Chief Justice’s claim that the “independent” commission was partisan. In an effort to comply with the Voting Rights Act, the challengers argue, the commission drew too many “influence” legislative districts, where Latino voters would have a real opportunity to elect one of their own or at least form a key voting bloc. This “packed” Republicans into the other districts—meaning that those districts have too many voters. This “gives voters in the Democrat [sic] districts a greater say than their counterparts in non-Hispanic-white Republican-plurality districts,” the challengers argue in their brief.

So the racial and partisan implications are clear. They are also clear in the second major redistricting case the Court will hear, Evenwel v. Abbott—and here the stakes are much larger. The issue in Evenwel is whether the Constitution’s Equal Protection Clause requires legislative and congressional districts that have an equal number of people or an equal number of voters. During the 1960s, the Court enunciated a rule that legislative districts can’t favor some areas or kinds of people over others; the principle came to be called “one person one vote.” Most states have used population as the basis for districts; in 1966, however, the Court allowed Hawaii to use registered voters to draw the districts. This was needed, the state argued, because of the large number of out-of-state visitors and military personnel on the islands would skew the districts. The Court said the state could make that choice “only because on this record [the registered voter basis] was found to have produced a distribution of legislators not substantially different from that which would have resulted from the use of a permissible population basis.”

The challengers in Evenwel want to go a good deal further. States, they argue, must use a voter basis rather than overall population in drawing districts. The challengers’ proposed bases—registered voters, eligible voters, or “citizen voting age population”—all produce districts that are whiter, older, and more Republican than population-based districts. Though the challengers’ briefing soft-pedals this racial angle, an amicus brief by the Cato Institute helpfully laid out the stakes for the justices: On the population basis, it argues, “eligible Hispanic voters in other districts have their votes ‘over-weighted’ and ‘over-valuated’” because those districts have large numbers of non-citizens.