The present invention discloses an apparatus and method for defining and enforcing rules of transition between two security domains, e.g., a transport domain and a persistent security domain. In turn, a border guard, e.g., a security device, is provided between these two domains that enforce rules for transition between the two security domains. This novel approach of defining a transport domain and a persistent security domain simplifies the classification of the digital content and its movement through the system. Namely, the border guard once established between the two systems can enforce DRM rules associated with how contents are moved between the two domains.