Evidence law concerns rules for fact-finding. In this sense, it is driven towards the “Epistemology of the Tribunal”. The primary purpose of “courtroom epistemology” is to ascertain the truth or to reduce the uncertainty in fact-finding. Fact-finding is a process of finding minor premise in legal reasoning. Accurate fact-finding is a prerequisite for fair trial. The rational characteristic of fact-finding in legal reasoning, determines that “the fact-finder must have epistemic justification for her findings”. The aim of legal reasoning is to provide legal reasons and justification for judgement. The justification of fact-finding and legal reasoning also derives from justice and human rights. “Truth-seeking” and “goodness-seeking” are the two issues of fact-finding, they together constitute the justification for a judgement. The function of fact-finding in legal reasoning should be emphasized, in addition to the fundamental theory of evidence law and legal reasoning with interdisciplinary approach.