A Source-Based Theory of Variation in Judicial Reasoning: Evidence from Sweden

Why do judges disagree about judicial reasoning – i.e., the use of legal reasoning in adjudication – and how can such disagreement be studied empirically? We propose a general theory of variation in judicial reasoning that focuses on a core element of legal analysis – the choice of authoritative sources. In particular, we argue that source-based disagreement is likely to manifest itself on two dimensions: The degree to which extra-national versus national and extra-legislative versus legislative sources should be relied on. Where judges place themselves on these dimensions have important normative implications for the origin of and power over law, and in particular the status and power of the national legislator. We demonstrate the strength and usefulness of our theory with original data from more than 3400 judicial opinions of the Swedish Supreme Court over a 40-year period. We find that Justices’ backgrounds, in terms of when they went to law school and professional pre-appointment experience, are correlated with their placement on these two dimensions in theoretically expected ways.