Abstract: The importance of evidence-based policy rooted in experimental methods is increasingly recognized, from the Oregon Medicaid experiment to the efforts to address global poverty that were awarded a 2019 Nobel Prize. Over the past several decades, there have been attempts to extend this scientific approach to legal systems and practice. Yet, despite progress in empirical legal studies and experimental social policy research, judges, lawyers, and legal services providers often fail to subject their own practices to empirical study or to be guided by empirical data, with a particular aversion to randomized controlled trials (RCTs) (1). This is troubling, as many questions fundamental to legal practice and those it affects, such as allocation of attorney services, bail decisions, and use of mandatory mediation, could and should be informed by a rigorous evidentiary foundation. Although there are practical obstacles to undertaking legal practice RCTs, they have also been stymied by cultural barriers...