The study addresses the issue of using legislative materials (legislative history) to interpret the law. This issue is considered from the point of view of the so-called derivational theory of legal interpretation formulated in Polish legal theory. The derivational theory of legal interpretation is treated as a framework and a starting point for developing an integrated theory of legal interpretation in Polish legal theory. The analyses contained in the article are theoretical in nature and apply a theoretical-legal method. The main thesis of the study is that the use of legislative materials should be included in the derivational model of interpretation, but with the application of the principle of their subsidiarity and the principle of assumed unanimity. The derivational theory is a comprehensive theory that formulates a normative (prescriptive) model of interpretation. The interpretive directives that make up this model refer to factors external to the actual legislator (in particular the rules of language) in order to objectify the interpretation process. It may seem that from the point of view of the derivational theory, the use of legislative history and the intent of the actual legislator for legal interpretation should be rejected. However, a closer analysis reveals that this is a false conclusion. One of the fundamental assumptions of the derivational theory is the postulate of striving for the greatest possible objectivity in the interpretation result. The subsidiary use of legislative materials may contribute to such objectification when reference to factors external to the actual legislator fails – it is inconclusive. However, the subsidiary use of legislative history is only possible if the analysis of legislative materials is conclusive, i.e. if it is possible to determine the clear legislative intent in accordance with the principle of assumed unanimity.