Katalin Sulyok, senior lecturer at ELTE Law School, Department of International Law was awarded the Henry Wheaton Prize by the Institut de Droit International in 2019; this prize is awarded by an international jury to the best English, German, French, Italian or Spanish language PhD dissertation in the field of international environmental law. This article presents and evaluates the major findings of the award-winning dissertation entitled ‘Scientific Engagement of International Courts and Tribunals in Environmental Disputes – Science and the Legitimacy of Adjudicatory Reasoning’.