While there is rich research on common law jury systems, less is known about lay participation in ‘mixed courts’. In this paper we shed new light on this topic and the role of lay judges by examining the effect of lay judges’ partisan affiliation on judicial decision making in Swedish administrative courts. In the courts of first instance in Sweden, a professional judge and a number of lay judges decide legal cases jointly. The lay judges are affiliated with the political parties and appointed in proportion to political party representation in the local elections. Exploiting the fact that laymen are randomly assigned to cases, we use an original data set of Swedish administrative court judgements in eldercare cases to explore whether the party affiliation of lay judges influences judicial decision making and the probability that individuals are granted access to eldercare services.