Methods and apparatus, including computer program products, for protecting electronic documents. A computer system includes a repository for storing an electronic document that has a document attribute. An access layer is used by an accessor to access at least one portion of the electronic document. The accessor has an accessor attribute. An expert system is operable to determine an access behavior with regards to the at least one portion by evaluating rules of a rule set with reference at least to the document attribute and the accessor attribute when the accessor tries to access the at least one portion using the access layer.