Comparison of legal argumentation in two closely related legal systems can help to understand legal reasoning in both of them and even generally. This article compares the patterns of legal argumentation and the use of sources of law in Swedish and Finnish jurisprudence. It argues that Swedish jurisprudence was until recently influenced by the inheritance of the Scandinavian realism whereas the Finnish legal thought has been permeated by somewhat formalistic school of rational legal argumentation. The quest for justice that young researchers in particular are interested in has challenge both traditions.  Fundamental rights, legal principles, social constructionist theory and discourse analytical have enriched legal research.