In this paper we study the traitor tracing problem, a technique to help combat piracy of copyrighted materials. When a pirated copy of the material is observed, a traitor tracing scheme allows one to identify at least one of the real users (traitors) who participate in the construction of the pirated copy. The authors have been involved in what we believe is the first large-scale deployment of the tracing traitors approach. In this paper we shall present a key management scheme that provides the system designer flexibility, in that he/she can choose to trace down to an individual user or only trace to a device's model. It helps effectively defend against class attack and evil manufacturer problem. It also provides a technology to protect consumers' privacy when needed. This flexibility is believed to be needed and has been adopted by content protection standard AACS for next generation DVDs.