TWO hundred and twenty-six years after America’s Constitution was ratified, it might come as a surprise to learn that a fundamental question about the nature of the American republic has never been resolved—or even posed. It is well known that the country is a representative democracy where the people elect officials who serve in local, state and national institutions to make laws and carry them out in their name. It is a bit less well understood that, for the past half-century, the principle of “one person, one vote” has meant that the states’ electoral districts must be roughly equal in population. If 100 people are served by one state senator, for example, while another represents a district of 1,000 people, the former group has ten times the clout of the latter. The Supreme Court ruled in 1964 that these types of inequalities violate the 14th Amendment’s equal protection clause.

That 1964 ruling in Reynolds v Sims, which announced the principle of “one person, one vote”, also said that states must count “people” (rather than “trees or acres”) and distribute them relatively evenly (with a margin of error of 5% either way) when drawing district maps. But the Supreme Court has not been very clear about whether “people” means everybody, or just eligible voters. The plaintiffs in a case argued before the court on December 8th say that Reynolds and other cases refer to the “people” as the body of individuals who are eligible to vote.

Densely populated districts typically have more people who are not eligible to vote than those that are more spread out. Since Democrats are the party of cities and Republicans the party of wide open spaces, a ruling for the challengers would strengthen the hand of Republicans.

With the encouragement of conservative activist Edward Blum and his organisation, the Project on Fair Representation, two Texas residents brought the suit in the hope that the Supreme Court will force states to draw up districts using this definition. Currently, in every state, maps distribute the total population in the state roughly evenly into a number of districts. Sue Evenwel and Edward Pfenninger, the plaintiffs, say their votes are being unconstitutionally weakened by this regime. The challengers point out that there are many more eligible voters in their district than in other Texas districts, where the population is goosed by large numbers of illegal aliens, felons and children—souls who do not enjoy the franchise. The state should be drawing districts to equalise the number of people eligible to vote, they say, not the total number of residents.

In his determined argument before the justices, William Consovoy, the lawyer for Ms Evenwel and Mr Pfenninger, encountered heavy resistance from the four more liberal justices. “You’re forgetting,” Justice Sonia Sotomayor told Mr Consovoy, “the dual interest”. States indeed have a “voting interest, but there is also a representation interest” at stake as well. Justice Elena Kagan drew attention to the wider theory underlying Article I of the constitution, which assigns states a number of seats in the House of Representatives according to the “whole number” of “persons”. “Why”, she asked, “would [it] be the case that the constitution requires something with respect to one apportionment that it prohibits with respect to another”?

Another line of attack came from Justice Ruth Bader Ginsburg. “I mean, in your interpretation of the 14th Amendment, from 1869 till 1920”—the year women won the franchise—“the state should not have been counting women for purposes of determining representation in the state legislature”. Justice Stephen Breyer chimed in that the challengers’ view—whereby children and aliens would still be represented even though they would have diminished access to representatives—smacked of the claim England once made to its rebellious colonies. “That sounds an awful lot [like] what they had in 1750 or something, where the British Parliament said, well, don’t worry, America, you’re represented by the people in England because after all, they represent everybody in the British empire”.

Evenwel, as is so often the case, will probably turn on the thinking of Justice Anthony Kennedy, the court’s habitual swing voter. Perhaps ominously for state Democrats, Justice Kennedy asked no questions of the plaintiff’s lawyer and reserved his queries for the lawyers defending total population as the correct measure. “There is an ethical, a good government, a liberty interest in protecting these voters”, said Justice Kennedy, and the plaintiffs’ interest is “being very substantially disregarded with this huge deviation”. It would be ideal, he suggested, if state districts could bring both total population and voting population numbers into balance. Why, he asked, “is one option exclusive of the other? Why can’t you have both?” The decision should arrive in the spring.