Previous judicial decision-making studies have used party labels as surrogates for ideological orientation. In this study of state-level reapportionment cases before the U.S. district courts, I investigate the partisan reference-group identification of judges as a nonlegal influence on decisions. The partisan identification of judges is juxtaposed with the political orientations of the legislatures passing reapportionment plans. The results suggest that partisan effects are included in the pattern of decisions in cases related to the state-level district plans. While judges tend to vote against plans submitted to them from legislatures where one political party has numerical control of the reapportionment process, they vote against plans presented from legislatures of their own party at a much lower rate than in cases where the party opposite their own controls the district drawing process. The logit model correctly predicts 89.3% of the cases and produces a 60.3% reduction of error.