If the court had come to the opposite conclusion and had held that districting had to be based on the number of eligible voters, it would have radically shifted political power and changed the very nature of representative government in this country.
In landmark rulings in the early 1960s, the Supreme Court articulated the principle of "one person, one vote." This means that the voting districts for any elected body must be about the same in population size. For example, all districts for a state legislative body must have approximately the same number of people.
The challengers in Evenwel v. Abbott argued that the Constitution requires that districts for state and local legislative bodies must be drawn based on eligible voters, not total population. They argued that all voters should be assured of equal influence in the political process.
The challenger's argument would not apply to congressional districts because the Constitution is clear that districts for the U.S. House of Representatives must be drawn based on population. Section two of the Fourteenth Amendment says "Representatives shall be apportioned among the several states according to their respective numbers, counting the whole number of persons in each state, excluding Indians not taxed."
The stakes in the case before the Supreme Court were enormous. If the challengers prevailed and districting had to be based on eligible voters rather than population, there would be a significant adverse effect on representation of minority communities.
Hispanic communities, with significant numbers of noncitizens, would lose representation. Felony convictions generally mean a loss of voting rights and this has a disproportionate effect on minority communities. Overall, if the challengers won and districting had to be based on eligible voters, the political power of cities would decrease, while suburban and rural areas, where white populations tend to dominate, would gain.
Also, there would be a significant practical problem with requiring that districting be based on the number of eligible voters: There is no way to know this number. The census provides a count of the population, but there is no similar mechanism that measures the number of eligible voters.
Therefore, it was not surprising that in Evenwel v. Abbott, the Supreme Court unanimously held that state and local governments may continue to draw districts based on population.
Justice Ruth Bader Ginsburg wrote for the court and stressed that history, judicial precedent and actual practice allow districting to be based on population. From the earliest days of the country, it was understood that election districts would be drawn based on population. It would be bizarre if the court had held that districts for state legislatures could not be drawn on the very basis that the Constitution requires for congressional districts. Never has the Supreme Court held or indicated that it is unconstitutional to draw election districts based on population.
Most of all, the court's decision is based on a basic principle of democracy:
Everyone -- adults and children, voters and nonvoters, citizens and noncitizens -- deserves representation.
Ginsburg stressed the importance of ensuring that an elected official represents all of his or her constituents. Thankfully, the court expressly reaffirmed this essential premise and did not change the law. State and local governments may continue to draw election districts based on population.