Do child support guidelines result in lower inter-judge disparity? The case of the French advisory child support guidelines

In this article, we study the decision-making of judges in an experimental setting resembling real world judicial decision-making in order to measure the impact of advisory guidelines on judges' decisions in divorce cases. We gave 312 French future judges 48 case vignettes, built from real data related to divorce cases involving children. We compared two different subject pools: judges who were asked to set child support awards with an advisory guideline and judges who were asked to set child support awards without any guidelines. We find that guidelines help to reduce the disparity between judges: the variance in similar cases is lower when the subjects have the opportunity to use guidelines. On the other hand, this effect is not systematic since we observe an increase in heterogeneity in some particular cases. We interpret this result by considering that the guidelines may generate a conflict of norms: the judge may be torn between the social norm represented by the guidelines and based on the child's interest and the legal norm that limits her decisions which need to stay within the parties' proposals. An increase of heterogeneity would result from different trade-offs between judges.