Recent legal scholarship demonstrates increased attention to empirical research in the design and evaluation of law and the policies and practices of legal authorities. The growth of evidence informed law is an exciting development and one that promises to improve the legal system. In this paper I argue for the particular value of drawing not just upon empirical research methods when evaluating existing policies and practices but upon social science theories. Theory based research provides a basis for imagining and testing different models about how the legal system might operate. I support this argument by presenting research on social science frameworks for legal authority which are alternatives to the currently prevalent instrumental model.