In its next term, the Supreme Court will hear arguments regarding a Texas case that could help restore the proper electoral balance in areas and communities with high concentrations of immigrants and children by mandating that districts at all levels be drawn based on the number of voters therein. This would be a departure from the practice adopted in the 1960s, after the Reynolds v. Sims decision mandated legislative districts be drawn strictly by equality of population. That ruling ended the practice of many states maintaining county-based state senate districts. Additionally, it gave rural areas more political clout at the expense of urban centers.

The new case, Evenwel v. Abbott, was brought by a Texas resident who claims her vote is diluted because her state senate district has 533,010 citizens of voting age, whereas other districts in the state have as few as 372,000 voting-aged citizens. The key words in this instance are “voting age” and “citizens,” as strict population-based guidelines could (and generally do) create districts with high concentrations of non-citizens or those otherwise ineligible to vote, such as convicted felons. Despite the fact current Texas districts were already drawn by Republicans, an outcome that allows states to form districts based on eligible voters would likely favor Republicans by diluting the voting strength of Latino-heavy districts that have a large number of noncitizen immigrants.

The state of Texas strongly objected to the Supreme Court taking the case. “Plaintiffs cite no case in which a court has accepted their claim that the Constitution compels states to apportion their legislative districts based on voter population as opposed to or in addition to total population,” wrote Texas Attorney General Ken Paxton. “Multiple precedents from this court confirm that total population is a permissible apportionment base under the Equal Protection Clause.”

But Associate Justice Clarence Thomas has been seeking a resolution to this issue for over a decade, arguing in a similar case in 2001 that the court has “never determined the relevant ‘population’ that states and localities must equally distribute among their districts.” He added, “[W]e have an obligation to explain to states and localities what (one person, one vote) actually means.”

Still, legal experts were somewhat surprised that the High Court took the case and wondered whether it could open a can of worms — particularly as census data doesn’t necessarily include the number of eligible voters in a particular area, just overall population. “State legislatures would be given a green light to locate more power or less power in areas that have large geographic concentrations of noncitizens,” said New York University law professor Richard Pildes. “Those areas would have more power if the rule is equality of residents and less power if it’s equality of eligible voters.”

Evenwel v. Abbott is expected to have its day in court early next year, and it could impact the 2018 midterm elections, when states gear up for the decennial redistricting process that begins after the 2020 Census.