Digital Libraries (DLs) introduce several challenging requirements with respect to the formulation, specification and enforcement of adequate access control policies. Unlike conventional database environments, a DL typically is characterised by a dynamic subject population, often making accesses from remote locations, and by an extraordinarily large amount of information, stored in a variety of formats. Additionally, protecting a DL does not only means protecting documents that reside at the DL site, but also protecting accesses that the DL subscribers made to external Web documents.

In this paper we present MaX, a comprehensive system for enforcing access control, specifically tailored to both DL and Web environments. Key features of MaX are the support for credential and content-based access control to DL and Web documents, and its full integration with standard Internet rating systems.