The mobile storage device may be provided with a system agent that is able to create at least one hierarchical tree comprising nodes at different levels for controlling access to data stored in the memory by corresponding entities. Each node of the tree specifies permission or permissions of a corresponding entity or entities for accessing memory data. The permission or permissions at the node of each of the trees has a predetermined relationship to permission or permissions at nodes at a higher or lower or the same level in the same tree. Thus, the mobile storage devices may be issued without any trees already created so that the purchaser of the devices has a free hand in creating hierarchical trees adapted to the applications the purchaser has in mind. Alternatively, the mobile storage devices may also be issued with the trees already created so that a purchaser does not have to go through the trouble of creating the trees. In both situations, preferably certain functionalities of the trees can become fixed after the devices are made so that they cannot be further changed or altered. This provides greater control over access to the content in the device by the content owner. Thus, in one embodiment, the system agent can preferably be disabled so that no additional trees can be created.