Abstract. In all user-centred agent-based applications, for instance in the context of ambient computing, the user agent is often faced to a difficult trade-off between the protection of its own privacy, and the fluidity offered by the services. In existing applications, the choice is almost never on the user's side, even though the law grants him a number of rights in order to guarantee his privacy. We examine here different technical works that seem to be as many interesting ways of dealing with privacy policies. The problems already solved will be identified, as well as remaining technical challenges. Then we will propose directions of research based on the most interesting aspects of the underlined approaches.