Media files are often tagged, such as by XML or other tagging paradigms, in order to indicate aspects of certain portions of the media file. Disclosed herein, security policy tagging is provided that supports a logically nested or hierarchical structure. Tags may be time- and/or event-altered, such as when a user who is denied access at one point in time may be granted access at a later point in time. The need to amend the security policy based upon the passage of time is reduced or eliminated as portions, or sub-portions, of a media file that may be selectively tagged with security tags may be presented or downloaded based upon the security policy. The a security policy may incorporate rules that change permissions upon the passage of time or the occurrence of an event, without requiring the modification of the presentation, the security tags of the presentation portion, or the security tag associated with a parent portion of the presentation or the presentation itself.