On April 6, some Republican voters in Tucson, Arizona, filed a federal lawsuit against that city’s hybrid system for choosing city councilmembers. Public Integrity Alliance Inc. v Tucson, 4:15cv-138. A hearing was held on Friday, May 8, and a decision is expected any day now.

Tucson, since 1929, holds partisan primaries for city council in odd years, within each ward. Candidates file based on which ward they live in, and the primary chooses a party nominee within each ward, for each party. But in the general election, candidates for each ward seat run at-large against each other. The plaintiffs point out that frequently, the general election produces winners who did not win in their own ward. The lawsuit argues that this violates the Fourteenth Amendment and the U.S. Supreme Court’s “one person, one vote” precedents.

Tucson is believed to be the only jurisdiction in the United States which uses a partisan hybrid system. The case is being expedited because the primary is in August 2015. Tucson has six wards, and city councilmembers have four-year terms. Three wards are voting in 2015.