There is a long-standing debate about the relative merits of lawyers and non-lawyers as adjudicators in international dispute settlement. Some argue that lawyers would encourage predictability and coherence in jurisprudence. Others believe that non-lawyers would better protect state interests. Both sides of the debate assume that lawyers are more formalist, while non-lawyers are more instrumentalist.

However, this assumption has never been empirically verified. Combining multiple-imputation, matching, and post-matching regression analysis, we find that panel chairs who lack law degrees and substantial experience make greater efforts to signal adherence to formalist rules and competence in the World Trade Organization’s jurisprudence than lawyers. The Appellate Body deems the signal credible, in turn rewarding inexperienced non-lawyers with a decrease in reversal rates. Overall, our findings suggest that non-lawyers display similar (if not greater) levels of formalism as lawyers, calling into question one of the classical reservations against non-lawyers serving in adjudicatory positions.