Justification of choices made throughout the design process of systems is a recurrent desire and quite often a formal request from certification authorities in the safety critical domain. However, even though some work has already been done in the early phases of the development processes, justifying choices in the later phases such as detailed design or implementation remain a cumbersome activity left (without any support) in the hands of the developers. This paper presents a notation called TEAM (Traceability, Exploration and Analysis Model) and its associated tool called DREAM (Design Rationale Environment for Argumentation and Modelling). The paper presents first the notation and its specificities with respect to other Design Rationale notations. Both the notation and the tools are presented on a case study showing how they can support design of interaction techniques for Air Traffic Control workstations. We also present the rationale that we have gathered while designing the graphical representation of the notation.