This article deals with the moral responsibility of information systems designers, in the context of professional use of these. In the exercise of this moral responsibility, economic and social dimensions will be specifically discussed here, in the sense that SI have an impact on the development and sustainability of organizations.The first part of this article is devoted to a state of the art on computer ethics. A second part presents our orientation (critical research) and our approach (which considers the SI as power devices), and concludes on the need to think an engineering of responsibility. In the third part, our contribution to this engineering is exposed in the form of a three-level model, which helps to reveal how a general vision and linked ethical values are gradually embodied in structuring principles, and binding standards.