Constitutional court judges maintain to be independent, apolitical actors, even though they get nominated by political elites. So far, much of the research has focused on the legal output of courts in order to show that judges are political animals. Studying outcomes is often plagued by endogeneity issues (e.g., when using votes to predict votes), or is simply not possible in some contexts due to the non-disclosure of individual voting records. Alternatively, scholars employ a party-label heuristic and infer from the ideological position of the nominating party to the ideological position of judges. But do those ideological differences between judges become behaviorally relevant? In this paper, we provide two peaces of evidence that judges nominated by different parties seem to behave differently. First, we study the composition of three-judge panels (Chambers) of the German Federal Constitutional Court using Chamber decisions from 1998-2011 and show that homogenous panels have been actively avoided. Second, we analyze the court’s replacement rules for absentee judges for the composition of chambers. We show that in situations where mechanically following the rules of procedure to replace absentee judges would lead to homogenous panels, the likelihood to deviate from those rules is systematically higher. Hence, judges elide formal rules to avoid homogenous chambers in order to appear politically unbiased.