In this paper the information system analysing and development theory of inseparability postulate is analysed and modified to enrich the variety of the field of information ethics. The paper looks at the Scandinavian information system development tradition and the background to further elaborate the creation and the basis of the inseparability postulate as well as connects it to modern information system problems in the field of information ethics. The discussion is tied to critical governmental information systems, which are systems that play crucial role in our society’s functioning in such manner that people’s health, security and wellbeing can be guaranteed. We argue that the inseparability postulate is a good tool to implement to the whole critical governmental information system lifecycle process due to its abstract yet functional nature.