We describe the conceptualization, development, and piloting of two instruments--a survey and a scenario-based assessment--designed to assess, teachers' recognition of an obligation to the discipline of mathematics and the extent to which teachers justify actions that deviate from what is normative on account of this obligation. We show how we have used classical test theory and item response theory to select items for the instruments and we provide information on their reliability, using a sample of 88 high school mathematics teachers. [For the complete proceedings, see ED597799.]