1. A computer system for protecting electronic documents, comprising: a repository for storing an electronic document having a document attribute; an access layer used by an accessor to access at least one portion of the electronic document, the accessor having an accessor attribute; a rule set; and an expert system operable to determine an access behavior with regards to the at least one portion by evaluating rules of the 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.