Conservatives on the U.S. Supreme Court have already undermined some important pillars of modern American life. Is the “one-person, one-vote” principle next? The answer, as of yesterday, is maybe.

The high court announced yesterday that the justices will hear arguments in a case called Evenwel v. Abbott. As Adam Liptak summarized

The case, a challenge to voting districts for the Texas Senate, was brought by two voters, Sue Evenwel and Edward Pfenninger. They are represented by the Project on Fair Representation, the small conservative advocacy group that successfully mounted the earlier challenge to the Voting Rights Act. It is also behind a pending challenge to affirmative action in admissions at the University of Texas at Austin. In the new case, the challengers said their voting power had been diluted. “There are voters or potential voters in Texas whose Senate votes are worth approximately one and one-half times that of appellants,” their brief said.

Under the status quo, legislative districts are based on total populations: the Census counts the number of people and lines are drawn accordingly.

But some conservatives want a more restrictive model. Counting everyone, they argue, ends up including people who can’t vote – noncitizens, ex-felons, and those under the age of 18 – which skews district lines. It’s better, the right insists, to look exclusively at the number of eligible and/or registered voters.

And why are they pushing this change? Because, as elections-law expert Rick Hasen explained yesterday, “A ruling that states may not draw legislative district lines taking total population into account will benefit rural voters over urban voters, and that will benefit Republicans over Democrats.”

Urban areas are much more likely to be filled with people who cannot vote: noncitizens (especially Latinos), released felons whose voting rights have not been restored, and children. With districts redrawn using only voters rather than all people, there will be more Republican districts. Evenwel involves the issue of state legislature redistricting, but you can bet that if the challengers are successful in this case, they will argue for the same principle to be applied to the drawing of national congressional districts. It is not clear whether the ruling would apply to congressional districts, because the one-person, one-vote principle for congressional districts has a different source in the Constitution (Article I) than the 14th Amendment’s Equal Protection Clause, which applies to state legislatures. But logically, the two cases are likely to be treated the same, and the result could be more congressional districts tending Republican, helping Republicans keep their advantage in the U.S. House of Representatives.