The purpose of this article is presentation of starting points and method tools for critical substantive validity testing of legal norms. The research problem in question is partly in what way the substantive validity of legal norms are determined, assessed and tested, partly the possible connection between the substantive validity of a norm and its efficiency in application in the legal practices in concrete cases. This is dealt with by presentation of starting points and method tools for critical substantive validity testing of legal norms. They are the result of independent, explorative research on my part. They have a general design. They are intended for use by a legal scholar within legal science. This is one way of performing a critical-practical-legal philosophy within legal science and by a legal scholar. They create the preconditions for and open the door for future research and provide the basis for deepened discussions in legal science.This article is divided into two parts.The purpose of the first part of this article is presentation of legal starting points for critical substantive validity testing of legal norms. The first part is titled “Critical substantive validity testing of legal norms. On presentation of starting points and method tools (I)”. The purpose of the second part of this article is presentation of legal scientific starting points and method tools for critical substantive validity testing of legal norms. The second part is titled “Critical substantive validity testing of legal norms. On presentation of starting points and method tools (II)”.