Texas' state Senate districts (click to enlarge)
In a move that election law expert Rick Hasen characterizes as "surprising," the Supreme Court has agreed to hear a potentially major case that could upend long-settled jurisprudence on the meaning of "one person, one vote." The suit, Evenwel v. Abbott, argues that the state of Texas should draw lines for its state Senate that equalize the voting population in each district, not the total population, as they do now.
And if the court were to side with the plaintiffs, Republicans would benefit. That's because there are fewer registered voters in urban, Democratic-leaning districts and far more in conservative rural seats. For instance, on the congressional level, California's sprawling 1st District—a vast, forested region nestled along the Oregon and Nevada borders—has about 521,000 eligible voters, according to one analyst, while the compact 40th District in Los Angeles has just 262,000. (When the lines were drawn in 2011, both had populations of 702,900.) And as you might expect, the former is represented by a Republican and the latter by a Democrat.
So if districts had to balance out voting-age populations, red seats would have to shed voters to blue seats, which are home to many more non-voters, chiefly non-citizens (often Hispanics), ex-felons without voting rights, and children. This would, of course, make those blue seats redder, which is why conservative groups are pushing this suit.
What's more, while this case is focused on legislative redistricting, there's no reason any ruling here couldn't also apply to congressional redistricting—and congressional reapportionment, which would mean that blue states would also likely lose a number of seats to red states. (Texas, ironically, with its large immigrant population, would be an exception, but the districts it would drop would be Democratic ones.)
However, there's a huge problem with this case's entire premise: It's almost impossible to count voters. Leah Libresco details the many reasons why, among them the fact that the Census doesn't ask about citizenship status. While the Census Bureau does get into more detail with its annual American Community Surveys, the ACS relies on statistical sampling—something the Supreme Court specifically barred for the purposes of the traditional decennial Census itself (which is currently used both for reapportionment and redistricting purposes).
Amusingly, Republicans were the victorious plaintiffs in that case (sampling would have uncovered many missing urban voters), so they might have unwittingly boxed themselves in. They also, as Libresco points out, hate the ACS and have tried to defund it, because heaven forbid the government should ever produce any useful statistical information that looks like science.
Of course, none of this may stop the Supreme Court's conservatives, who have shown no hesitation in curtailing minority voting rights. It'll be a while before they rule, though, but if they enshrine "one registered voter, one vote" into law, we'll be in for some serious upheaval.