The paper provides a conceptual distinction between evidence assessment criteria and standards of proof. Evidence must be assessed in order to check whether it satisfies a relevant standard of proof, and the assessment is operated with some criterion; so both criteria and standards are necessary for fact-finding. In addition to this conceptual point, the article addresses three main questions: (1) Why do some scholars and decision-makers take assessment criteria as standards of proof and vice versa? (2) Why do systems differ as to criteria and standards? (3) How can a system work if it neglects one of these things? The answers to the first and second question come from the historical and procedural differences between the systems. The answer to the third focuses on the functional connection between criteria and standards.