The behavior of judges in asymmetric tie-breaking power conditions has been barely studied empirically. Most courts are designed as an odd-numbered panel where –theoretically– each judge hold the same probability of deciding the court’s outcome. Accordingly, less attention has been given to the behavior of judges in even-numbered panels where votes’ weight is –by design– distributed unequally among judges. Based on an original database on votes in non-unanimous decisions by a Chilean administrative tribunal formed by 4 judges where its president hold tie-breaking power, this research test whether differences in votes’ weight among judges explain judicial coalition formation, while controlling for the judges’ ideological preferences. In doing so, the study enhance our understanding of the institutional determinants of the judicial decision-making.