This paper describes the rationales supporting the design of a Copy Protection System. It reflects the experience of the Security Laboratory of Thomson in the development of SmartRight. This paper does not only account the chosen technical solutions. It also explores less technical but highly important issues such as the social, legal and commercial aspects. Hence, while carefully developing our motivations, some light is shed on the very peculiar problems raised by the enforcement of copy protection. It gives then an overview of the global SmartRight system and some technical details on its main innovative features.