The Supreme Court rejected a conservative challenge to the 'one person, one vote' rule that counts non-voters such as children and prisoners. Here's what you need to know. (Victoria Walker/The Washington Post)

The Supreme Court issued a decision Monday on the widely anticipated “one person, one vote” case, unanimously ruling that states can draw their voting districts based on total population as opposed to just the number of people who can vote.

The case, Evenwel v. Abbott, featured arguments on a pair of state Senate districts in the Dallas area. Because Texas draws its districts based on total population — including non-citizens who are not eligible to vote — some voters in the suburban districts argue that their votes are “diluted” compared with those of neighboring urban districts that are home to many immigrants.

The case essentially revolved around who should be represented by our lawmakers, and there was a lot at stake. If the Supreme Court ruled that drawing districts according to total population was unconstitutional — thereby mandating that virtually all states redraw their districts — experts projected that Republicans would have gained a signification advantage in state elections throughout the country.

In Theory published a series on the topic in October, trying to pin down what constitutes fairness in representation. Here are a few key excerpts from the symposium.

From Nathaniel Persily, professor of law at Stanford University:

It would be one thing if the appellants in this case spent their efforts trying to lobby the Texas legislature to conduct a census of Texas citizens and redistrict on that basis. But knowing the political outcry that would result from a tactic rightfully perceived as targeting Latinos, given the neighborhoods likely to lose representation under that principle, the appellants instead want to use the courts — and the Constitution — to eliminate from political consideration any theory of representation other than the one they favor.

From Peter A. Morrison, a demographer at the Rand Corp.:

State and local governments can and should avoid constructing districts of flagrantly disproportionate voting strength. They have reliable data at their fingertips to reduce those imbalances. If states wish to equalize total population in order to advance representational equality, they should be permitted to do so — but only as long as doing so does not compromise electoral equality.

From Richard H. Pildes of New York University:

[Representatives] have to address the realities created by all those who live in their districts, not just those eligible to vote. Non-citizens and the young in places like Los Angeles and Chicago inevitably impose burdens on government services — for law enforcement, schools and the provision of basic services such as water delivery or emergency medical care. Indeed, that is part of the reason immigration is a major political issue. If representatives do not have the political power necessary to advocate for the total number of people in their districts, their ability to meet their representative obligations is dramatically curtailed.

Of course, it must be noted that the ruling Monday didn’t explicitly mandate that states use total population in drawing districts — only that they can if they so chose. Virtually all states draw districts in this way, with a few minor variations, but the door is open for states to partition districts based on eligible voters.

The issue is still not completely settled. Justice Samuel Alito has already suggested that the court may have to revisit the topic if a state decides to exclude non-voters from its redistricting math.