The Supreme Court has unanimously upheld a Texas law that counts everyone, not just eligible voters, in deciding how to draw electoral districts.
The justices turned back a challenge Monday that could have dramatically altered political district boundaries and disproportionately affected the nation's growing Latino population.
The court ruled that Texas' challenged state Senate districting map complied with the principle of "one person, one vote." That's the requirement that political districts be roughly equal in population.
The challengers said the districts had vastly different population counts when looking at eligible voters, in violation of the Constitution.
"Jurisdictions may design state and local legislative districts with equal total populations, we hold; they are not obliged to equalize voter populations," Justice Ruth Bader Ginsburg said, summarizing her opinion for the court.
Ginsburg said that "history, our decisions and settled practice in all 50 states and countless local jurisdictions point in the same direction."
Two rural Texas voters challenged the use of total population data in drawing state Senate districts because they say it inflates the voting power of city dwellers at their expense.
In Texas, and other states with large immigrant populations, urban districts include many more people who are too young, not citizens or otherwise ineligible to vote. Civil rights groups said forcing states to change their method of constructing districts would have damaged Latino political influence.
The court stopped short of saying that states must use total population. And it also did not rule on whether states are free to use a different measure, as Texas asked.
Ginsburg said the court was not resolving whether states may use voter population.